配置文件的修改

我现在有一个文件 TEST.config, 里面数据为

我现在通过代码把LENG 改成其它数字

#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)
{
        int fdSrc;
        char *readBuf = NULL;

        if(argc != 2){
                printf("params error\n");
                exit(-1);
        }

        fdSrc = open(argv[1],O_RDWR);
        int size = lseek(fdSrc, 0, SEEK_END);
        lseek(fdSrc, 0, SEEK_SET);

        readBuf = (char *)malloc(sizeof(char) * size + 8);
        int n_read = read(fdSrc, readBuf, size);

        char *p = strstr(readBuf,"LENG="); // 通过字符串查找到需要修改的字符
        if(p == NULL){
                printf("not found\n");
                exit(-1);
        }
        p = p + strlen("LENG=");  // 指针编译
        *p = '8';  // 注意，读出来的都是字符
        lseek(fdSrc, 0, SEEK_SET);
        int n_write = write(fdSrc, readBuf, strlen(readBuf));

        close(fdSrc);
        return 0;
}

结果是ok的