[源码分析]-轻量级JSON-cJson

[源码分析]-轻量级JSON-cJson

second60 20180612

1. cJSON简介

cJson是个轻量级的C语言JSON库，速度快，而且代码少，只有两个文件：cJSON.h和cJSON.c。代码只有七百多行。

使用只需引入cJSON文件，一起编译即可，使用了数学库，要添加-lm库

g++ test.c cJSON.c -o test

gcc test.c cJSON.c -o test -lm

2. JSON知识

JSON(JavaScript Object Notation, JS 对象简谱) 是一种轻量级的数据交换格式。它基于 ECMAScript (欧洲计算机协会制定的js规范)的一个子集，采用完全独立于编程语言的文本格式来存储和表示数据。简洁和清晰的层次结构使得 JSON 成为理想的数据交换语言。 易于人阅读和编写，同时也易于机器解析和生成，并有效地提升网络传输效率。

2.1 json 语法

在 JS 语言中，一切都是对象。因此，任何支持的类型都可以通过 JSON 来表示，例如字符串、数字、对象、数组等。但是对象和数组是比较特殊且常用的两种类型：

对象表示为键值对

数据由逗号分隔

花括号保存对象

方括号保存数组

 

对象：JSON最常用的格式是对象的键值对

{"firstName": "Json"}

数组：数组的方式也是使用方括号 []

{
    "people":[
    {
        "firstName": "Brett",
        "lastName":"McLaughlin"
    },
    {  
        "firstName":"Jason",
        "lastName":"Hunter"
    }
    ]
}

2.2 json的好处

a) 通用性，任何语言只要按照json格式，都可以互通使用

b) json的转换速度非常快

c) json比xml体积小

d) json的扩展性非常好，新加item只需多加key/value

2.3 json的劣点

a) json体积会比正常的流体积大很多，包括：引号，冒名，键名等，所以比网络中比较浪费流量

b) json递归深度有限制，如果深度很深，那么速度将会变慢，同时占用内存比较大

c) json字符串没有顺序，所以较难读懂

 

2.4 使用场所景

在大部份的项目中，都会使用json，因为json有语言无关性，只要都是json格式，都可以读取使用。

 

a) json配置。因为json解析速度比xml要快，要小，所以把配置转成json字符串，程序中读取将会非常快，配置可以放本地，也可以放redis中。

b) 网络格式。虽然json会比较大，但对于网络接口，可以用json格式，目的是json有很好的扩展性，加一个参数或返回值，是非常容易，而且不影响原有逻辑。

c) 跨语言交互。如两个不同语言交互，可以用json来进行交互。

 

总结，json是一个用途非常广泛，也非常好用的标准。

3. cJSON源码分析

3.1 cJSON数据结构

cJSON中包含两个结构，cJSON结构和cJSON_Hooks结构

// cJson 结构体
typedef struct cJSON {
  // 双链表指针
struct cJSON *next,*prev;	/* next/prev allow you to walk array/object chains. Alternatively, use GetArraySize/GetArrayItem/GetObjectItem */
// 孩子指什
  struct cJSON *child;	/* An array or object item will have a child pointer pointing to a chain of the items in the array/object. */
  // 类型
int type;	/* The type of the item, as above. */
  // 当类型为cJSON_String,此值有用
char *valuestring;	/* The item's string, if type==cJSON_String */
  // 当类型为cJSON_Number，下面值有用
int valueint;	/* The item's number, if type==cJSON_Number */
double valuedouble;	/* The item's number, if type==cJSON_Number */
  // item名字
char *string;	/* The item's name string, if this item is the child of, or is in the list of subitems of an object. */
} cJSON;

// cJson 函数指针钩子，用来实现不同的函数
typedef struct cJSON_Hooks {
      void *(*malloc_fn)(size_t sz);
      void (*free_fn)(void *ptr);
} cJSON_Hooks;

3.2 cJSON函数库

/* Supply malloc, realloc and free functions to cJSON */
extern void cJSON_InitHooks(cJSON_Hooks* hooks);
/* Supply a block of JSON, and this returns a cJSON object you can interrogate. Call cJSON_Delete when finished. */
extern cJSON *cJSON_Parse(const char *value);
/* Render a cJSON entity to text for transfer/storage. Free the char* when finished. */
extern char  *cJSON_Print(cJSON *item);
/* Render a cJSON entity to text for transfer/storage without any formatting. Free the char* when finished. */
extern char  *cJSON_PrintUnformatted(cJSON *item);
/* Render a cJSON entity to text using a buffered strategy. prebuffer is a guess at the final size. guessing well reduces reallocation. fmt=0 gives unformatted, =1 gives formatted */
extern char *cJSON_PrintBuffered(cJSON *item,int prebuffer,int fmt);
/* Delete a cJSON entity and all subentities. */
extern void   cJSON_Delete(cJSON *c);

/* Returns the number of items in an array (or object). */
extern int	  cJSON_GetArraySize(cJSON *array);
/* Retrieve item number "item" from array "array". Returns NULL if unsuccessful. */
extern cJSON *cJSON_GetArrayItem(cJSON *array,int item);
/* Get item "string" from object. Case insensitive. */
extern cJSON *cJSON_GetObjectItem(cJSON *object,const char *string);

/* For analysing failed parses. This returns a pointer to the parse error. You'll probably need to look a few chars back to make sense of it. Defined when cJSON_Parse() returns 0. 0 when cJSON_Parse() succeeds. */
extern const char *cJSON_GetErrorPtr(void);
/* These calls create a cJSON item of the appropriate type. */
extern cJSON *cJSON_CreateNull(void);
extern cJSON *cJSON_CreateTrue(void);
extern cJSON *cJSON_CreateFalse(void);
extern cJSON *cJSON_CreateBool(int b);
extern cJSON *cJSON_CreateNumber(double num);
extern cJSON *cJSON_CreateString(const char *string);
extern cJSON *cJSON_CreateArray(void);
extern cJSON *cJSON_CreateObject(void);

/* These utilities create an Array of count items. */
extern cJSON *cJSON_CreateIntArray(const int *numbers,int count);
extern cJSON *cJSON_CreateFloatArray(const float *numbers,int count);
extern cJSON *cJSON_CreateDoubleArray(const double *numbers,int count);
extern cJSON *cJSON_CreateStringArray(const char **strings,int count);
 
/* Append item to the specified array/object. */
extern void cJSON_AddItemToArray(cJSON *array, cJSON *item);
extern void	cJSON_AddItemToObject(cJSON *object,const char *string,cJSON *item);
extern void	cJSON_AddItemToObjectCS(cJSON *object,const char *string,cJSON *item);	/* Use this when string is definitely const (i.e. a literal, or as good as), and will definitely survive the cJSON object */
/* Append reference to item to the specified array/object. Use this when you want to add an existing cJSON to a new cJSON, but don't want to corrupt your existing cJSON. */
extern void cJSON_AddItemReferenceToArray(cJSON *array, cJSON *item);
extern void	cJSON_AddItemReferenceToObject(cJSON *object,const char *string,cJSON *item);

/* Remove/Detatch items from Arrays/Objects. */
extern cJSON *cJSON_DetachItemFromArray(cJSON *array,int which);
extern void   cJSON_DeleteItemFromArray(cJSON *array,int which);
extern cJSON *cJSON_DetachItemFromObject(cJSON *object,const char *string);
extern void   cJSON_DeleteItemFromObject(cJSON *object,const char *string);

/* Update array items. */
extern void cJSON_InsertItemInArray(cJSON *array,int which,cJSON *newitem);	/* Shifts pre-existing items to the right. */
extern void cJSON_ReplaceItemInArray(cJSON *array,int which,cJSON *newitem);
extern void cJSON_ReplaceItemInObject(cJSON *object,const char *string,cJSON *newitem);

/* Duplicate a cJSON item */
extern cJSON *cJSON_Duplicate(cJSON *item,int recurse);
/* Duplicate will create a new, identical cJSON item to the one you pass, in new memory that will
need to be released. With recurse!=0, it will duplicate any children connected to the item.
The item->next and ->prev pointers are always zero on return from Duplicate. */

/* ParseWithOpts allows you to require (and check) that the JSON is null terminated, and to retrieve the pointer to the final byte parsed. */
extern cJSON *cJSON_ParseWithOpts(const char *value,const char **return_parse_end,int require_null_terminated);
extern void cJSON_Minify(char *json);

/* Macros for creating things quickly. */
#define cJSON_AddNullToObject(object,name)	cJSON_AddItemToObject(object, name, cJSON_CreateNull())
#define cJSON_AddTrueToObject(object,name)	cJSON_AddItemToObject(object, name, cJSON_CreateTrue())
#define cJSON_AddFalseToObject(object,name)	cJSON_AddItemToObject(object, name, cJSON_CreateFalse())
#define cJSON_AddBoolToObject(object,name,b)	cJSON_AddItemToObject(object, name, cJSON_CreateBool(b))
#define cJSON_AddNumberToObject(object,name,n)	cJSON_AddItemToObject(object, name, cJSON_CreateNumber(n))
#define cJSON_AddStringToObject(object,name,s)	cJSON_AddItemToObject(object, name, cJSON_CreateString(s))

/* When assigning an integer value, it needs to be propagated to valuedouble too. */
#define cJSON_SetIntValue(object,val)	((object)?(object)->valueint=(object)->valuedouble=(val):(val))
#define cJSON_SetNumberValue(object,val)	((object)?(object)->valueint=(object)->valuedouble=(val):(val))

3.3 cJSON实现

/* cJSON */
/* JSON parser in C. */
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <float.h>
#include <limits.h>
#include <ctype.h>
#include "cJSON.h"

// 错误指针
static const char *ep;
// 返回错误指针
const char *cJSON_GetErrorPtr(void) { return ep; }
// 字符串大小比较
static int cJSON_strcasecmp(const char *s1, const char *s2)
{
	if (!s1) return (s1 == s2) ? 0 : 1; if (!s2) return 1;
	for (; tolower(*s1) == tolower(*s2); ++s1, ++s2)	if (*s1 == 0)	return 0;
	return tolower(*(const unsigned char *)s1) - tolower(*(const unsigned char *)s2);
}

// 初始化malloc和free函数
static void *(*cJSON_malloc)(size_t sz) = malloc;
static void(*cJSON_free)(void *ptr) = free;

// 复制字符串
static char* cJSON_strdup(const char* str)
{
	size_t len;
	char* copy;
	len = strlen(str) + 1;
	if (!(copy = (char*)cJSON_malloc(len))) return 0;
	memcpy(copy, str, len);
	return copy;
}

// 初始化犯错钩子函数
void cJSON_InitHooks(cJSON_Hooks* hooks)
{
	if (!hooks) { /* Reset hooks */
		cJSON_malloc = malloc;
		cJSON_free = free;
		return;
	}
	cJSON_malloc = (hooks->malloc_fn) ? hooks->malloc_fn : malloc;
	cJSON_free = (hooks->free_fn) ? hooks->free_fn : free;
}

/* Internal constructor. */
// 创建设一个item
static cJSON *cJSON_New_Item(void)
{
	cJSON* node = (cJSON*)cJSON_malloc(sizeof(cJSON));
	if (node) memset(node, 0, sizeof(cJSON));
	return node;
}

/* Delete a cJSON structure. */
// 遍历删除cJson
void cJSON_Delete(cJSON *c)
{
	cJSON *next;
	while (c)
	{
		next = c->next;
		if (!(c->type&cJSON_IsReference) && c->child) cJSON_Delete(c->child);
		if (!(c->type&cJSON_IsReference) && c->valuestring) cJSON_free(c->valuestring);
		if (!(c->type&cJSON_StringIsConst) && c->string) cJSON_free(c->string);
		cJSON_free(c);
		c = next;
	}
}

/* Parse the input text to generate a number, and populate the result into item. */
// 把num转成整型放到item中
static const char *parse_number(cJSON *item, const char *num)
{
	double n = 0, sign = 1, scale = 0; int subscale = 0, signsubscale = 1;
	// 把num转成整型
	if (*num == '-') sign = -1, num++;	/* Has sign? */
	if (*num == '0') num++;	/* is zero */
	if (*num >= '1' && *num <= '9')	do	n = (n*10.0) + (*num++ - '0');	while (*num >= '0' && *num <= '9');	/* Number? */
	if (*num == '.' && num[1] >= '0' && num[1] <= '9') { num++;	do	n = (n*10.0) + (*num++ - '0'), scale--; while (*num >= '0' && *num <= '9'); }	/* Fractional part? */
	if (*num == 'e' || *num == 'E')	/* Exponent? */
	{
		num++; if (*num == '+') num++;	else if (*num == '-') signsubscale = -1, num++;	/* With sign? */
		while (*num >= '0' && *num <= '9') subscale = (subscale * 10) + (*num++ - '0');	/* Number? */
	}


	n = sign*n*pow(10.0, (scale + subscale*signsubscale));	/* number = +/- number.fraction * 10^+/- exponent */
	// 会同时设置两个值，一个整型，一个浮点型
	item->valuedouble = n;
	item->valueint = (int)n;
	item->type = cJSON_Number;
	return num;
}

//返回比x大的最小的2的N次方数
static int pow2gt(int x)	{ --x;	x |= x >> 1;	x |= x >> 2;	x |= x >> 4;	x |= x >> 8;	x |= x >> 16;	return x + 1; }
typedef struct { char *buffer; int length; int offset; } printbuffer;
static char* ensure(printbuffer *p, int needed)
{
	char *newbuffer; int newsize;
	if (!p || !p->buffer) return 0;
	needed += p->offset;
	if (needed <= p->length) return p->buffer + p->offset;
	newsize = pow2gt(needed);
	newbuffer = (char*)cJSON_malloc(newsize);
	if (!newbuffer) { cJSON_free(p->buffer); p->length = 0, p->buffer = 0; return 0; }
	if (newbuffer) memcpy(newbuffer, p->buffer, p->length);
	cJSON_free(p->buffer);
	p->length = newsize;
	p->buffer = newbuffer;
	return newbuffer + p->offset;
}

static int update(printbuffer *p)
{
	char *str;
	if (!p || !p->buffer) return 0;
	str = p->buffer + p->offset;
	return p->offset + strlen(str);
}

/* Render the number nicely from the given item into a string. */
// 把数据转换成字符串
static char *print_number(cJSON *item, printbuffer *p)
{
	char *str = 0;
	double d = item->valuedouble;
	// 0分配两位
	// 这里d==0会不会有问题呢 d是一个double类型
	if (d == 0)
	{
		if (p)	str = ensure(p, 2);
		else	str = (char*)cJSON_malloc(2);	/* special case for 0. */
		if (str) strcpy(str, "0");
	}
	// 2^64+1 占21个字符
	else if (fabs(((double)item->valueint) - d) <= DBL_EPSILON && d <= INT_MAX && d >= INT_MIN)
	{
		if (p)	str = ensure(p, 21);
		else	str = (char*)cJSON_malloc(21);	/* 2^64+1 can be represented in 21 chars. */
		if (str)	sprintf(str, "%d", item->valueint);
	}
	// 科学计数 64位
	else
	{
		if (p)	str = ensure(p, 64);
		else	str = (char*)cJSON_malloc(64);	/* This is a nice tradeoff. */
		if (str)
		{
			if (fabs(floor(d) - d) <= DBL_EPSILON && fabs(d)<1.0e60)sprintf(str, "%.0f", d);
			else if (fabs(d)<1.0e-6 || fabs(d)>1.0e9)	sprintf(str, "%e", d);
			else	sprintf(str, "%f", d);
		}
	}
	return str;
}

// 解析四位十六进制数 "ffff"
static unsigned parse_hex4(const char *str)
{
	unsigned h = 0;
	if (*str >= '0' && *str <= '9') h += (*str) - '0'; else if (*str >= 'A' && *str <= 'F') h += 10 + (*str) - 'A'; else if (*str >= 'a' && *str <= 'f') h += 10 + (*str) - 'a'; else return 0;
	h = h << 4; str++;
	if (*str >= '0' && *str <= '9') h += (*str) - '0'; else if (*str >= 'A' && *str <= 'F') h += 10 + (*str) - 'A'; else if (*str >= 'a' && *str <= 'f') h += 10 + (*str) - 'a'; else return 0;
	h = h << 4; str++;
	if (*str >= '0' && *str <= '9') h += (*str) - '0'; else if (*str >= 'A' && *str <= 'F') h += 10 + (*str) - 'A'; else if (*str >= 'a' && *str <= 'f') h += 10 + (*str) - 'a'; else return 0;
	h = h << 4; str++;
	if (*str >= '0' && *str <= '9') h += (*str) - '0'; else if (*str >= 'A' && *str <= 'F') h += 10 + (*str) - 'A'; else if (*str >= 'a' && *str <= 'f') h += 10 + (*str) - 'a'; else return 0;
	return h;
}

/* Parse the input text into an unescaped cstring, and populate item. */
static const unsigned char firstByteMark[7] = { 0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC };

// 把str字符串解析放入item中
static const char *parse_string(cJSON *item, const char *str)
{
	const char *ptr = str + 1; char *ptr2; char *out; int len = 0; unsigned uc, uc2;
	if (*str != '\"') { ep = str; return 0; }	/* not a string! */
	while (*ptr != '\"' && *ptr && ++len) if (*ptr++ == '\\') ptr++;	/* Skip escaped quotes. */
	out = (char*)cJSON_malloc(len + 1);	/* This is how long we need for the string, roughly. */
	if (!out) return 0;
	ptr = str + 1; ptr2 = out;
	while (*ptr != '\"' && *ptr)
	{
		if (*ptr != '\\') *ptr2++ = *ptr++;
		else
		{
			ptr++;
			switch (*ptr)
			{
			case 'b': *ptr2++ = '\b';	break;
			case 'f': *ptr2++ = '\f';	break;
			case 'n': *ptr2++ = '\n';	break;
			case 'r': *ptr2++ = '\r';	break;
			case 't': *ptr2++ = '\t';	break;
			case 'u':	 /* transcode utf16 to utf8. */
				uc = parse_hex4(ptr + 1); ptr += 4;	/* get the unicode char. */
				if ((uc >= 0xDC00 && uc <= 0xDFFF) || uc == 0)	break;	/* check for invalid.	*/
				if (uc >= 0xD800 && uc <= 0xDBFF)	/* UTF16 surrogate pairs.	*/
				{
					if (ptr[1] != '\\' || ptr[2] != 'u')	break;	/* missing second-half of surrogate.	*/
					uc2 = parse_hex4(ptr + 3); ptr += 6;
					if (uc2<0xDC00 || uc2>0xDFFF)	break;	/* invalid second-half of surrogate.	*/
					uc = 0x10000 + (((uc & 0x3FF) << 10) | (uc2 & 0x3FF));
				}

				len = 4; if (uc<0x80) len = 1; else if (uc<0x800) len = 2; else if (uc<0x10000) len = 3; ptr2 += len;
				switch (len) {
				case 4: *--ptr2 = ((uc | 0x80) & 0xBF); uc >>= 6;
				case 3: *--ptr2 = ((uc | 0x80) & 0xBF); uc >>= 6;
				case 2: *--ptr2 = ((uc | 0x80) & 0xBF); uc >>= 6;
				case 1: *--ptr2 = (uc | firstByteMark[len]);
				}
				ptr2 += len;
				break;
			default:  *ptr2++ = *ptr; break;
			}
			ptr++;
		}
	}
	*ptr2 = 0;
	if (*ptr == '\"') ptr++;
	item->valuestring = out;
	item->type = cJSON_String;
	return ptr;
}

/* Render the cstring provided to an escaped version that can be printed. */
static char *print_string_ptr(const char *str, printbuffer *p)
{
	const char *ptr; char *ptr2, *out; int len = 0, flag = 0; unsigned char token;
	for (ptr = str; *ptr; ptr++) flag |= ((*ptr>0 && *ptr<32) || (*ptr == '\"') || (*ptr == '\\')) ? 1 : 0;
	if (!flag)
	{
		len = ptr - str;
		if (p) out = ensure(p, len + 3);
		else	out = (char*)cJSON_malloc(len + 3);
		if (!out) return 0;
		ptr2 = out; *ptr2++ = '\"';
		strcpy(ptr2, str);
		ptr2[len] = '\"';
		ptr2[len + 1] = 0;
		return out;
	}

	if (!str)
	{
		if (p)	out = ensure(p, 3);
		else	out = (char*)cJSON_malloc(3);
		if (!out) return 0;
		strcpy(out, "\"\"");
		return out;
	}
	ptr = str; while ((token = *ptr) && ++len) { if (strchr("\"\\\b\f\n\r\t", token)) len++; else if (token<32) len += 5; ptr++; }
	if (p)	out = ensure(p, len + 3);
	else	out = (char*)cJSON_malloc(len + 3);
	if (!out) return 0;

	ptr2 = out; ptr = str;
	*ptr2++ = '\"';
	while (*ptr)
	{
		if ((unsigned char)*ptr>31 && *ptr != '\"' && *ptr != '\\') *ptr2++ = *ptr++;
		else
		{
			*ptr2++ = '\\';
			switch (token = *ptr++)
			{
			case '\\':	*ptr2++ = '\\';	break;
			case '\"':	*ptr2++ = '\"';	break;
			case '\b':	*ptr2++ = 'b';	break;
			case '\f':	*ptr2++ = 'f';	break;
			case '\n':	*ptr2++ = 'n';	break;
			case '\r':	*ptr2++ = 'r';	break;
			case '\t':	*ptr2++ = 't';	break;
			default: sprintf(ptr2, "u%04x", token); ptr2 += 5;	break;	/* escape and print */
			}
		}
	}
	*ptr2++ = '\"'; *ptr2++ = 0;
	return out;
}

/* Invote print_string_ptr (which is useful) on an item. */
static char *print_string(cJSON *item, printbuffer *p)	{ return print_string_ptr(item->valuestring, p); }

/* Predeclare these prototypes. */
static const char *parse_value(cJSON *item, const char *value);
static char *print_value(cJSON *item, int depth, int fmt, printbuffer *p);
static const char *parse_array(cJSON *item, const char *value);
static char *print_array(cJSON *item, int depth, int fmt, printbuffer *p);
static const char *parse_object(cJSON *item, const char *value);
static char *print_object(cJSON *item, int depth, int fmt, printbuffer *p);

/* Utility to jump whitespace and cr/lf */
static const char *skip(const char *in) { while (in && *in && (unsigned char)*in <= 32) in++; return in; }

/* Parse an object - create a new root, and populate. */
cJSON *cJSON_ParseWithOpts(const char *value, const char **return_parse_end, int require_null_terminated)
{
	const char *end = 0;
	cJSON *c = cJSON_New_Item();
	ep = 0;
	if (!c) return 0;       /* memory fail */

	end = parse_value(c, skip(value));
	if (!end)	{ cJSON_Delete(c); return 0; }	/* parse failure. ep is set. */

	/* if we require null-terminated JSON without appended garbage, skip and then check for a null terminator */
	if (require_null_terminated) { end = skip(end); if (*end) { cJSON_Delete(c); ep = end; return 0; } }
	if (return_parse_end) *return_parse_end = end;
	return c;
}

/* Default options for cJSON_Parse */
cJSON *cJSON_Parse(const char *value) { return cJSON_ParseWithOpts(value, 0, 0); }

/* Render a cJSON item/entity/structure to text. */
char *cJSON_Print(cJSON *item)	{ return print_value(item, 0, 1, 0); }
char *cJSON_PrintUnformatted(cJSON *item)	{ return print_value(item, 0, 0, 0); }
char *cJSON_PrintBuffered(cJSON *item, int prebuffer, int fmt)
{
	printbuffer p;
	p.buffer = (char*)cJSON_malloc(prebuffer);
	p.length = prebuffer;
	p.offset = 0;
	return print_value(item, 0, fmt, &p);
	return p.buffer;
}

/* Parser core - when encountering text, process appropriately. */
// 解析value的值到item中
static const char *parse_value(cJSON *item, const char *value)
{
	if (!value)	return 0;	/* Fail on null. */
	if (!strncmp(value, "null", 4))	{ item->type = cJSON_NULL;  return value + 4; }
	if (!strncmp(value, "false", 5))	{ item->type = cJSON_False; return value + 5; }
	if (!strncmp(value, "true", 4))	{ item->type = cJSON_True; item->valueint = 1;	return value + 4; }
	if (*value == '\"')	{ return parse_string(item, value); }
	if (*value == '-' || (*value >= '0' && *value <= '9'))	{ return parse_number(item, value); }
	if (*value == '[')	{ return parse_array(item, value); }
	if (*value == '{')	{ return parse_object(item, value); }
	ep = value; return 0;	/* failure. */
}

/* Render a value to text. */
static char *print_value(cJSON *item, int depth, int fmt, printbuffer *p)
{
	char *out = 0;
	if (!item) return 0;
	if (p)
	{
		switch ((item->type) & 255)
		{
		case cJSON_NULL:	{out = ensure(p, 5);	if (out) strcpy(out, "null");	break; }
		case cJSON_False:	{out = ensure(p, 6);	if (out) strcpy(out, "false");	break; }
		case cJSON_True:	{out = ensure(p, 5);	if (out) strcpy(out, "true");	break; }
		case cJSON_Number:	out = print_number(item, p); break;
		case cJSON_String:	out = print_string(item, p); break;
		case cJSON_Array:	out = print_array(item, depth, fmt, p); break;
		case cJSON_Object:	out = print_object(item, depth, fmt, p); break;
		}
	}
	else
	{
		switch ((item->type) & 255)
		{
		case cJSON_NULL:	out = cJSON_strdup("null");	break;
		case cJSON_False:	out = cJSON_strdup("false"); break;
		case cJSON_True:	out = cJSON_strdup("true"); break;
		case cJSON_Number:	out = print_number(item, 0); break;
		case cJSON_String:	out = print_string(item, 0); break;
		case cJSON_Array:	out = print_array(item, depth, fmt, 0); break;
		case cJSON_Object:	out = print_object(item, depth, fmt, 0); break;
		}
	}
	return out;
}

/* Build an array from input text. */
// 解析数组 []
static const char *parse_array(cJSON *item, const char *value)
{
	cJSON *child;
	if (*value != '[')	{ ep = value; return 0; }	/* not an array! */
	item->type = cJSON_Array;
	value = skip(value + 1);
	if (*value == ']') return value + 1;	/* empty array. */
	item->child = child = cJSON_New_Item();
	if (!item->child) return 0;	 /* memory fail */
	value = skip(parse_value(child, skip(value)));	/* skip any spacing, get the value. */
	if (!value) return 0;
	while (*value == ',')
	{
		cJSON *new_item;
		if (!(new_item = cJSON_New_Item())) return 0; /* memory fail */
		child->next = new_item; new_item->prev = child; child = new_item;
		value = skip(parse_value(child, skip(value + 1)));
		if (!value) return 0;	/* memory fail */
	}

	if (*value == ']') return value + 1;	/* end of array */
	ep = value; return 0;	/* malformed. */
}

/* Render an array to text */
// 将数据转换成字符
static char *print_array(cJSON *item, int depth, int fmt, printbuffer *p)
{
	char **entries;
	char *out = 0, *ptr, *ret; int len = 5;
	cJSON *child = item->child;
	int numentries = 0, i = 0, fail = 0;
	size_t tmplen = 0;
	/* How many entries in the array? */
	while (child) numentries++, child = child->next;
	/* Explicitly handle numentries==0 */
	if (!numentries)
	{
		if (p)	out = ensure(p, 3);
		else	out = (char*)cJSON_malloc(3);
		if (out) strcpy(out, "[]");
		return out;
	}

	if (p)
	{
		/* Compose the output array. */
		i = p->offset;
		ptr = ensure(p, 1); if (!ptr) return 0;	*ptr = '[';	p->offset++;
		child = item->child;
		while (child && !fail)
		{
			print_value(child, depth + 1, fmt, p);
			p->offset = update(p);
			if (child->next) { len = fmt ? 2 : 1; ptr = ensure(p, len + 1); if (!ptr) return 0; *ptr++ = ','; if (fmt)*ptr++ = ' '; *ptr = 0; p->offset += len; }
			child = child->next;
		}

		ptr = ensure(p, 2); if (!ptr) return 0;	*ptr++ = ']'; *ptr = 0;

		out = (p->buffer) + i;

	}

	else

	{

		/* Allocate an array to hold the values for each */

		entries = (char**)cJSON_malloc(numentries*sizeof(char*));

		if (!entries) return 0;

		memset(entries, 0, numentries*sizeof(char*));

		/* Retrieve all the results: */

		child = item->child;

		while (child && !fail)

		{

			ret = print_value(child, depth + 1, fmt, 0);

			entries[i++] = ret;

			if (ret) len += strlen(ret) + 2 + (fmt ? 1 : 0); else fail = 1;

			child = child->next;

		}

		/* If we didn't fail, try to malloc the output string */

		if (!fail)	out = (char*)cJSON_malloc(len);

		/* If that fails, we fail. */

		if (!out) fail = 1;



		/* Handle failure. */

		if (fail)

		{

			for (i = 0; i<numentries; i++) if (entries[i]) cJSON_free(entries[i]);

			cJSON_free(entries);

			return 0;

		}

		/* Compose the output array. */

		*out = '[';

		ptr = out + 1; *ptr = 0;

		for (i = 0; i<numentries; i++)

		{

			tmplen = strlen(entries[i]); memcpy(ptr, entries[i], tmplen); ptr += tmplen;

			if (i != numentries - 1) { *ptr++ = ','; if (fmt)*ptr++ = ' '; *ptr = 0; }

			cJSON_free(entries[i]);

		}

		cJSON_free(entries);

		*ptr++ = ']'; *ptr++ = 0;

	}

	return out;

}



/* Build an object from the text. */

// 解析对象{}

static const char *parse_object(cJSON *item, const char *value)

{

	cJSON *child;

	if (*value != '{')	{ ep = value; return 0; }	/* not an object! */

	item->type = cJSON_Object;

	value = skip(value + 1);

	if (*value == '}') return value + 1;	/* empty array. */

	item->child = child = cJSON_New_Item();

	if (!item->child) return 0;

	value = skip(parse_string(child, skip(value)));

	if (!value) return 0;

	child->string = child->valuestring; child->valuestring = 0;

	if (*value != ':') { ep = value; return 0; }	/* fail! */

	value = skip(parse_value(child, skip(value + 1)));	/* skip any spacing, get the value. */

	if (!value) return 0;

	while (*value == ',')

	{

		cJSON *new_item;

		if (!(new_item = cJSON_New_Item()))	return 0; /* memory fail */

		child->next = new_item; new_item->prev = child; child = new_item;

		value = skip(parse_string(child, skip(value + 1)));

		if (!value) return 0;

		child->string = child->valuestring; child->valuestring = 0;

		if (*value != ':') { ep = value; return 0; }	/* fail! */

		value = skip(parse_value(child, skip(value + 1)));	/* skip any spacing, get the value. */

		if (!value) return 0;

	}

	if (*value == '}') return value + 1;	/* end of array */

	ep = value; return 0;	/* malformed. */

}



/* Render an object to text. */

// 将对象转换成字符

static char *print_object(cJSON *item, int depth, int fmt, printbuffer *p)

{

	char **entries = 0, **names = 0;

	char *out = 0, *ptr, *ret, *str; int len = 7, i = 0, j;

	cJSON *child = item->child;

	int numentries = 0, fail = 0;

	size_t tmplen = 0;

	/* Count the number of entries. */

	while (child) numentries++, child = child->next;

	/* Explicitly handle empty object case */

	if (!numentries)

	{

		if (p) out = ensure(p, fmt ? depth + 4 : 3);

		else	out = (char*)cJSON_malloc(fmt ? depth + 4 : 3);

		if (!out)	return 0;

		ptr = out; *ptr++ = '{';

		if (fmt) { *ptr++ = '\n'; for (i = 0; i<depth - 1; i++) *ptr++ = '\t'; }

		*ptr++ = '}'; *ptr++ = 0;

		return out;

	}

	if (p)

	{

		/* Compose the output: */

		i = p->offset;

		len = fmt ? 2 : 1;	ptr = ensure(p, len + 1);	if (!ptr) return 0;

		*ptr++ = '{';	if (fmt) *ptr++ = '\n';	*ptr = 0;	p->offset += len;

		child = item->child; depth++;

		while (child)

		{

			if (fmt)

			{

				ptr = ensure(p, depth);	if (!ptr) return 0;

				for (j = 0; j<depth; j++) *ptr++ = '\t';

				p->offset += depth;

			}

			print_string_ptr(child->string, p);

			p->offset = update(p);

			len = fmt ? 2 : 1;

			ptr = ensure(p, len);	if (!ptr) return 0;

			*ptr++ = ':'; if (fmt) *ptr++ = '\t';

			p->offset += len;

			print_value(child, depth, fmt, p);

			p->offset = update(p);



			len = (fmt ? 1 : 0) + (child->next ? 1 : 0);

			ptr = ensure(p, len + 1); if (!ptr) return 0;

			if (child->next) *ptr++ = ',';

			if (fmt) *ptr++ = '\n'; *ptr = 0;

			p->offset += len;

			child = child->next;

		}

		ptr = ensure(p, fmt ? (depth + 1) : 2);	 if (!ptr) return 0;

		if (fmt)	for (i = 0; i<depth - 1; i++) *ptr++ = '\t';

		*ptr++ = '}'; *ptr = 0;

		out = (p->buffer) + i;

	}

	else

	{

		/* Allocate space for the names and the objects */

		entries = (char**)cJSON_malloc(numentries*sizeof(char*));

		if (!entries) return 0;

		names = (char**)cJSON_malloc(numentries*sizeof(char*));

		if (!names) { cJSON_free(entries); return 0; }

		memset(entries, 0, sizeof(char*)*numentries);

		memset(names, 0, sizeof(char*)*numentries);



		/* Collect all the results into our arrays: */

		child = item->child; depth++; if (fmt) len += depth;

		while (child)

		{

			names[i] = str = print_string_ptr(child->string, 0);

			entries[i++] = ret = print_value(child, depth, fmt, 0);

			if (str && ret) len += strlen(ret) + strlen(str) + 2 + (fmt ? 2 + depth : 0); else fail = 1;

			child = child->next;

		}

		/* Try to allocate the output string */

		if (!fail)	out = (char*)cJSON_malloc(len);

		if (!out) fail = 1;



		/* Handle failure */

		if (fail)
		{
			for (i = 0; i<numentries; i++) { if (names[i]) cJSON_free(names[i]); if (entries[i]) cJSON_free(entries[i]); }
			cJSON_free(names); cJSON_free(entries);
			return 0;
		}

		/* Compose the output: */
		*out = '{'; ptr = out + 1; if (fmt)*ptr++ = '\n'; *ptr = 0;
		for (i = 0; i<numentries; i++)
		{
			if (fmt) for (j = 0; j<depth; j++) *ptr++ = '\t';
			tmplen = strlen(names[i]); memcpy(ptr, names[i], tmplen); ptr += tmplen;
			*ptr++ = ':'; if (fmt) *ptr++ = '\t';
			strcpy(ptr, entries[i]); ptr += strlen(entries[i]);
			if (i != numentries - 1) *ptr++ = ',';
			if (fmt) *ptr++ = '\n'; *ptr = 0;
			cJSON_free(names[i]); cJSON_free(entries[i]);
		}
		cJSON_free(names); cJSON_free(entries);
		if (fmt) for (i = 0; i<depth - 1; i++) *ptr++ = '\t';
		*ptr++ = '}'; *ptr++ = 0;
	}
	return out;
}



/* Get Array size/item / object item. */

int    cJSON_GetArraySize(cJSON *array)	{ cJSON *c = array->child; int i = 0; while (c)i++, c = c->next; return i; }

cJSON *cJSON_GetArrayItem(cJSON *array, int item)	{ cJSON *c = array->child;  while (c && item>0) item--, c = c->next; return c; }

cJSON *cJSON_GetObjectItem(cJSON *object, const char *string)	{ cJSON *c = object->child; while (c && cJSON_strcasecmp(c->string, string)) c = c->next; return c; }



/* Utility for array list handling. */

static void suffix_object(cJSON *prev, cJSON *item) { prev->next = item; item->prev = prev; }

/* Utility for handling references. */

static cJSON *create_reference(cJSON *item) { cJSON *ref = cJSON_New_Item(); if (!ref) return 0; memcpy(ref, item, sizeof(cJSON)); ref->string = 0; ref->type |= cJSON_IsReference; ref->next = ref->prev = 0; return ref; }



/* Add item to array/object. */

void   cJSON_AddItemToArray(cJSON *array, cJSON *item)	{ cJSON *c = array->child; if (!item) return; if (!c) { array->child = item; } else { while (c && c->next) c = c->next; suffix_object(c, item); } }

void   cJSON_AddItemToObject(cJSON *object, const char *string, cJSON *item)	{ if (!item) return; if (item->string) cJSON_free(item->string); item->string = cJSON_strdup(string); cJSON_AddItemToArray(object, item); }

void   cJSON_AddItemToObjectCS(cJSON *object, const char *string, cJSON *item)	{ if (!item) return; if (!(item->type&cJSON_StringIsConst) && item->string) cJSON_free(item->string); item->string = (char*)string; item->type |= cJSON_StringIsConst; cJSON_AddItemToArray(object, item); }

void	cJSON_AddItemReferenceToArray(cJSON *array, cJSON *item) { cJSON_AddItemToArray(array, create_reference(item)); }

void	cJSON_AddItemReferenceToObject(cJSON *object, const char *string, cJSON *item) { cJSON_AddItemToObject(object, string, create_reference(item)); }



cJSON *cJSON_DetachItemFromArray(cJSON *array, int which)	{
	cJSON *c = array->child; while (c && which>0) c = c->next, which--; if (!c) return 0;

	if (c->prev) c->prev->next = c->next; if (c->next) c->next->prev = c->prev; if (c == array->child) array->child = c->next; c->prev = c->next = 0; return c;
}

void   cJSON_DeleteItemFromArray(cJSON *array, int which) { cJSON_Delete(cJSON_DetachItemFromArray(array, which)); }

cJSON *cJSON_DetachItemFromObject(cJSON *object, const char *string) { int i = 0; cJSON *c = object->child; while (c && cJSON_strcasecmp(c->string, string)) i++, c = c->next; if (c) return cJSON_DetachItemFromArray(object, i); return 0; }

void   cJSON_DeleteItemFromObject(cJSON *object, const char *string) { cJSON_Delete(cJSON_DetachItemFromObject(object, string)); }



/* Replace array/object items with new ones. */

void   cJSON_InsertItemInArray(cJSON *array, int which, cJSON *newitem)	{
	cJSON *c = array->child; while (c && which>0) c = c->next, which--; if (!c) { cJSON_AddItemToArray(array, newitem); return; }

	newitem->next = c; newitem->prev = c->prev; c->prev = newitem; if (c == array->child) array->child = newitem; else newitem->prev->next = newitem;
}

void   cJSON_ReplaceItemInArray(cJSON *array, int which, cJSON *newitem)	{
	cJSON *c = array->child; while (c && which>0) c = c->next, which--; if (!c) return;

	newitem->next = c->next; newitem->prev = c->prev; if (newitem->next) newitem->next->prev = newitem;

	if (c == array->child) array->child = newitem; else newitem->prev->next = newitem; c->next = c->prev = 0; cJSON_Delete(c);
}

void   cJSON_ReplaceItemInObject(cJSON *object, const char *string, cJSON *newitem){ int i = 0; cJSON *c = object->child; while (c && cJSON_strcasecmp(c->string, string))i++, c = c->next; if (c){ newitem->string = cJSON_strdup(string); cJSON_ReplaceItemInArray(object, i, newitem); } }



/* Create basic types: */

cJSON *cJSON_CreateNull(void)	{ cJSON *item = cJSON_New_Item(); if (item)item->type = cJSON_NULL; return item; }

cJSON *cJSON_CreateTrue(void)	{ cJSON *item = cJSON_New_Item(); if (item)item->type = cJSON_True; return item; }

cJSON *cJSON_CreateFalse(void)	{ cJSON *item = cJSON_New_Item(); if (item)item->type = cJSON_False; return item; }

cJSON *cJSON_CreateBool(int b)	{ cJSON *item = cJSON_New_Item(); if (item)item->type = b ? cJSON_True : cJSON_False; return item; }

cJSON *cJSON_CreateNumber(double num)	{ cJSON *item = cJSON_New_Item(); if (item){ item->type = cJSON_Number; item->valuedouble = num; item->valueint = (int)num; }return item; }

cJSON *cJSON_CreateString(const char *string)	{ cJSON *item = cJSON_New_Item(); if (item){ item->type = cJSON_String; item->valuestring = cJSON_strdup(string); }return item; }

cJSON *cJSON_CreateArray(void)	{ cJSON *item = cJSON_New_Item(); if (item)item->type = cJSON_Array; return item; }

cJSON *cJSON_CreateObject(void)	{ cJSON *item = cJSON_New_Item(); if (item)item->type = cJSON_Object; return item; }



/* Create Arrays: */

cJSON *cJSON_CreateIntArray(const int *numbers, int count)	{ int i; cJSON *n = 0, *p = 0, *a = cJSON_CreateArray(); for (i = 0; a && i<count; i++){ n = cJSON_CreateNumber(numbers[i]); if (!i)a->child = n; else suffix_object(p, n); p = n; }return a; }

cJSON *cJSON_CreateFloatArray(const float *numbers, int count)	{ int i; cJSON *n = 0, *p = 0, *a = cJSON_CreateArray(); for (i = 0; a && i<count; i++){ n = cJSON_CreateNumber(numbers[i]); if (!i)a->child = n; else suffix_object(p, n); p = n; }return a; }

cJSON *cJSON_CreateDoubleArray(const double *numbers, int count)	{ int i; cJSON *n = 0, *p = 0, *a = cJSON_CreateArray(); for (i = 0; a && i<count; i++){ n = cJSON_CreateNumber(numbers[i]); if (!i)a->child = n; else suffix_object(p, n); p = n; }return a; }

cJSON *cJSON_CreateStringArray(const char **strings, int count)	{ int i; cJSON *n = 0, *p = 0, *a = cJSON_CreateArray(); for (i = 0; a && i<count; i++){ n = cJSON_CreateString(strings[i]); if (!i)a->child = n; else suffix_object(p, n); p = n; }return a; }

/* Duplication */
// 复制item 是否递归recurse
cJSON *cJSON_Duplicate(cJSON *item, int recurse)
{
	cJSON *newitem, *cptr, *nptr = 0, *newchild;
	/* Bail on bad ptr */
	if (!item) return 0;
	/* Create new item */
	newitem = cJSON_New_Item();
	if (!newitem) return 0;
	/* Copy over all vars */
	newitem->type = item->type&(~cJSON_IsReference), newitem->valueint = item->valueint, newitem->valuedouble = item->valuedouble;
	if (item->valuestring)	{ newitem->valuestring = cJSON_strdup(item->valuestring);	if (!newitem->valuestring) { cJSON_Delete(newitem); return 0; } }
	if (item->string)	{ newitem->string = cJSON_strdup(item->string);	if (!newitem->string)	{ cJSON_Delete(newitem); return 0; } }
	/* If non-recursive, then we're done! */
	if (!recurse) return newitem;

	/* Walk the ->next chain for the child. */
	cptr = item->child;
	while (cptr)
	{
		newchild = cJSON_Duplicate(cptr, 1);	/* Duplicate (with recurse) each item in the ->next chain */
		if (!newchild) { cJSON_Delete(newitem); return 0; }
		if (nptr)	{ nptr->next = newchild, newchild->prev = nptr; nptr = newchild; }	/* If newitem->child already set, then crosswire ->prev and ->next and move on */
		else	{ newitem->child = newchild; nptr = newchild; }	/* Set newitem->child and move to it */
		cptr = cptr->next;
	}
	return newitem;
}

// json 缩进
void cJSON_Minify(char *json)
{
	char *into = json;
	while (*json)
	{
		if (*json == ' ') json++;
		else if (*json == '\t') json++;	/* Whitespace characters. */
		else if (*json == '\r') json++;
		else if (*json == '\n') json++;
		else if (*json == '/' && json[1] == '/')  while (*json && *json != '\n') json++;	/* double-slash comments, to end of line. */
		else if (*json == '/' && json[1] == '*') { while (*json && !(*json == '*' && json[1] == '/')) json++; json += 2; }	/* multiline comments. */
		else if (*json == '\"'){ *into++ = *json++; while (*json && *json != '\"'){ if (*json == '\\') *into++ = *json++; *into++ = *json++; }*into++ = *json++; } /* string literals, which are \" sensitive. */
		else *into++ = *json++;	/* All other characters. */
	}
	*into = 0;	/* and null-terminate. */
}

3.4 cJSON使用

#include <stdio.h>
#include <stdlib.h>
#include "cJSON.h"
/* Parse text to JSON, then render back to text, and print! */
// 把文本转找成json格式
void doit(char *text)
{
	char *out; cJSON *json;
	json = cJSON_Parse(text);
	if (!json) { printf("Error before: [%s]\n", cJSON_GetErrorPtr()); }
	else
	{
		out = cJSON_Print(json);
		cJSON_Delete(json);
		printf("%s\n", out);
		free(out);
	}
}


/* Read a file, parse, render back, etc. */
void dofile(char *filename)
{
	FILE *f; long len; char *data;
	f = fopen(filename, "rb"); fseek(f, 0, SEEK_END); len = ftell(f); fseek(f, 0, SEEK_SET);
	data = (char*)malloc(len + 1); fread(data, 1, len, f); fclose(f);
	doit(data);
	free(data);
}


/* Used by some code below as an example datatype. */
struct record { const char *precision; double lat, lon; const char *address, *city, *state, *zip, *country; };


/* Create a bunch of objects as demonstration. */
void create_objects()
{
	cJSON *root, *fmt, *img, *thm, *fld; char *out; int i;	/* declare a few. */
	/* Our "days of the week" array: */
	const char *strings[7] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };
	/* Our matrix: */
	int numbers[3][3] = { { 0, -1, 0 }, { 1, 0, 0 }, { 0, 0, 1 } };
	/* Our "gallery" item: */
	int ids[4] = { 116, 943, 234, 38793 };
	/* Our array of "records": */
	struct record fields[2] = {
		{ "zip", 37.7668, -1.223959e+2, "", "SAN FRANCISCO", "CA", "94107", "US" },
		{ "zip", 37.371991, -1.22026e+2, "", "SUNNYVALE", "CA", "94085", "US" } };
	/* Here we construct some JSON standards, from the JSON site. */
	/* Our "Video" datatype: */
	root = cJSON_CreateObject();
	cJSON_AddItemToObject(root, "name", cJSON_CreateString("Jack (\"Bee\") Nimble"));
	cJSON_AddItemToObject(root, "format", fmt = cJSON_CreateObject());
	cJSON_AddStringToObject(fmt, "type", "rect");
	cJSON_AddNumberToObject(fmt, "width", 1920);
	cJSON_AddNumberToObject(fmt, "height", 1080);
	cJSON_AddFalseToObject(fmt, "interlace");
	cJSON_AddNumberToObject(fmt, "frame rate", 24);
	out = cJSON_Print(root);	cJSON_Delete(root);	printf("%s\n", out);	free(out);	/* Print to text, Delete the cJSON, print it, release the string. */


	/* Our "days of the week" array: */
	root = cJSON_CreateStringArray(strings, 7);
	out = cJSON_Print(root);	cJSON_Delete(root);	printf("%s\n", out);	free(out);


	/* Our matrix: */
	root = cJSON_CreateArray();
	for (i = 0; i<3; i++) cJSON_AddItemToArray(root, cJSON_CreateIntArray(numbers[i], 3));


	/*	cJSON_ReplaceItemInArray(root,1,cJSON_CreateString("Replacement")); */
	out = cJSON_Print(root);	cJSON_Delete(root);	printf("%s\n", out);	free(out);


	/* Our "gallery" item: */
	root = cJSON_CreateObject();
	cJSON_AddItemToObject(root, "Image", img = cJSON_CreateObject());
	cJSON_AddNumberToObject(img, "Width", 800);
	cJSON_AddNumberToObject(img, "Height", 600);
	cJSON_AddStringToObject(img, "Title", "View from 15th Floor");
	cJSON_AddItemToObject(img, "Thumbnail", thm = cJSON_CreateObject());
	cJSON_AddStringToObject(thm, "Url", "http:/*www.example.com/image/481989943");
	cJSON_AddNumberToObject(thm, "Height", 125);
	cJSON_AddStringToObject(thm, "Width", "100");
	cJSON_AddItemToObject(img, "IDs", cJSON_CreateIntArray(ids, 4));
	out = cJSON_Print(root);	cJSON_Delete(root);	printf("%s\n", out);	free(out);


	/* Our array of "records": */
	root = cJSON_CreateArray();
	for (i = 0; i<2; i++)
	{
		cJSON_AddItemToArray(root, fld = cJSON_CreateObject());
		cJSON_AddStringToObject(fld, "precision", fields[i].precision);
		cJSON_AddNumberToObject(fld, "Latitude", fields[i].lat);
		cJSON_AddNumberToObject(fld, "Longitude", fields[i].lon);
		cJSON_AddStringToObject(fld, "Address", fields[i].address);
		cJSON_AddStringToObject(fld, "City", fields[i].city);
		cJSON_AddStringToObject(fld, "State", fields[i].state);
		cJSON_AddStringToObject(fld, "Zip", fields[i].zip);
		cJSON_AddStringToObject(fld, "Country", fields[i].country);
	}


	/*	cJSON_ReplaceItemInObject(cJSON_GetArrayItem(root,1),"City",cJSON_CreateIntArray(ids,4)); */
	out = cJSON_Print(root);	cJSON_Delete(root);	printf("%s\n", out);	free(out);
}


int main(int argc, const char * argv[]) {
	/* a bunch of json: */
	char text1[] = "{\n\"name\": \"Jack (\\\"Bee\\\") Nimble\", \n\"format\": {\"type\":       \"rect\", \n\"width\":      1920, \n\"height\":     1080, \n\"interlace\":  false,\"frame rate\": 24\n}\n}";
	char text2[] = "[\"Sunday\", \"Monday\", \"Tuesday\", \"Wednesday\", \"Thursday\", \"Friday\", \"Saturday\"]";
	char text3[] = "[\n    [0, -1, 0],\n    [1, 0, 0],\n    [0, 0, 1]\n	]\n";
	char text4[] = "{\n	\"Image\": {\n	\"Width\":  800,\n	\"Height\": 600,\n	\"Title\":  \"View from 15th Floor\",\n \"Thumbnail\": {\n	\"Url\":    \"http:/*www.example.com/image/481989943\",\n	\"Height\": 125,\n	\"Width\":  \"100\"\n	},\n	\"IDs\": [116, 943, 234, 38793]\n	}\n	}";
	char text5[] = "[\n	 {\n	 \"precision\": \"zip\",\n	 \"Latitude\":  37.7668,\n	 \"Longitude\": -122.3959,\n	 \"Address\":   \"\",\n	 \"City\":      \"SAN FRANCISCO\",\n	 \"State\":     \"CA\",\n	 \"Zip\":       \"94107\",\n	 \"Country\":   \"US\"\n  },\n	 {\n	 \"precision\": \"zip\",\n	 \"Latitude\":  37.371991,\n	 \"Longitude\": -122.026020,\n	 \"Address\":   \"\",\n  \"City\":      \"SUNNYVALE\",\n	 \"State\":     \"CA\",\n	 \"Zip\":       \"94085\",\n	 \"Country\":   \"US\"\n	 }\n	 ]";


	/* Process each json textblock by parsing, then rebuilding: */
	doit(text1);
	doit(text2);
	doit(text3);
	doit(text4);
	doit(text5);


	/* Now some samplecode for building objects concisely: */
	create_objects();
	return 0;
}