假设我的test.config文件内容是:
SPEED=3
LENG=5
SCORE=8
LEVEL=5
通过文件操作,来把LENG=5修改为LENG=3
实现该功能的基本是思路如下:
1.读取配置文件到缓存中
2.strstr查找子字符串寻找位置,查找asdf=返回的是a的位置
3.指针位置+便宜(strlen("LENG="))
4.*p 取内容,被赋值= 修改
5.写入操作是文件,是字符
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
int main(int argc ,char **argv)
{
char *readBuff = NULL;
int fdSrc;
if(argc != 2){ //./a.out test.config argc=2
printf("pararm error\n");
exit(-1);
}
fdSrc = open(argv[1],O_RDWR);
int size = lseek(fdSrc,0,SEEK_END);
readBuff =(char *)malloc(sizeof(char)*size+8);
lseek(fdSrc,0,SEEK_SET);
int n_read = read(fdSrc,readBuff,size);
char *p = strstr(readBuff,"LENG=");
if(p == NULL){
printf("not found\n");
exit(-1);
}
p = p + strlen("LENG=");
*p = '3'; //写入的是字符因此是''
lseek(fdSrc,0,SEEK_SET);
int n_write = write(fdSrc,readBuff,strlen(readBuff));
close(fdSrc);
return 0;
}