首先在shell下man fgets。
#include <stdio.h>
char*fgets(char *s, int size, FILE *stream);
函数参数：s：存放输入字符的缓冲区地址
size：输入的字符串长度
stream：输入文件流
属性：fgets() reads in at most one less than size characters from stream and stores
theminto the buffer pointed to by s. Readingstops after an EOF or a newline.
If a newline is read, it is storedinto the buffer. A terminating null byte
('\0')is stored after the last character in the buffer.
gets()函数的第二个参数指定了一次读取的最大字符数量。当fgets()读取到'\n'或已经读取了size-1个字符后就会返回，并在整个读到的数据后面添加'\0'作为字符串结束符。因此fgets()的读取大小保证了不会造成缓冲区溢出，但是也意味着fgets()函数可能不会读取到完整的一行（即可能无法读取该行的结束符'\n'）。
返回值：fgets() return s on success, and NULLon error or when end of file
occurs while no characters have been read.
函数返回值：成功：s
失败或读到文件尾：NULL
示例：利用fgets读取一个文件的行数。
程序如下：
/*************************************************************************
@Author: wanghao
@Created Time : Sun 20 May 2018 02:14:16 AMPDT
@File Name: test1.c
@Description:
************************************************************************/
#include <stdio.h>
#include <string.h>
#define MAX 128
int main(int argc, const char *argv[])
{
intlen;
FILE*fp;
charbuf[MAX] = {0};
if(argc< 2)
{
printf("usage:%s <src> <dest>\n",argv[0]);
return-1;
}
fp= fopen(argv[1], "r+");
if(fp< 0)
{
printf("open%s fail!\n",argv[1]);
return-2;
}
len= 0;
while(fgets(buf,MAX, fp))
{
/**In the buf string, if read a row, the last is the ‘\0’, and the second last is ‘\n’
if(buf[strlen(buf)- 1] == '\n')
len++;
}
printf("len= %d\n",len);
return0;
}