c/c++ 去除字符串左右两边空格

tools.h：

# ifndef __TOOLS_H
# define __TOOLS_H

extern "C" char* ltrim(char* s);
extern "C" char* rtrim(char* s);
extern "C"  char* alltrim(char* s);
或者
char* ltrim(char* s);
char* rtrim(char* s);
char* alltrim(char* s);
# endif

tools.cpp

#include "tools.h"
#include <cstdio>
#include <cstring>

/*去除字符串左边的空格*/
char* ltrim(char* s)
{
	int i = 0, j = 0;

	if(s == NULL)
		return (char *)NULL;

	while(' ' == s[i] || '\t' == s[i])
		i++;

	if(0 == i)
		return s;

	while('\0' != s[j + i])
		{
		s[j] = s[j + i];
		j++;
		}

	s[j] = '\0';

	return s;
}

/*去除字符串右边的空格*/
char* rtrim(char* s)
{
	int i;

	if(s == NULL)
		return (char *)NULL;

	for(i = strlen(s); i > 0; i--)
		{
		if(s[i - 1] == ' ' || s[i - 1] == '\t')
			s[i - 1] = '\0';
		else
			break;
		}

	return s;
}

/*去除字符串两边的空格*/
char* alltrim(char* s)
{
	ltrim(s);
	rtrim(s);
	return s;
}

测试demo.cpp
#include "tools.h"
#include <iostream>

using namespace std;

int main()
{
    char szWaitTrim[50] = "     abcdefghijklmnopqrstuvwxyz     ";
    char *lpAllTrimResult;
    lpAllTrimResult = alltrim(szWaitTrim);
    cout <<"lpAllTrimResult:" << lpAllTrimResult <<endl;
    return 0;
}

编译运行及结果：
g++ -o demo demo.cpp tools.cpp
./demo
lpAllTrimResult:abcdefghijklmnopqrstuvwxyz

传递的是指针，原szWaitTrim内容已经变化了，如果还要对原数组进行其他操作的话需要注意。