1 #include <stdio.h>  2   3 int main()  4 {  5         FILE *fp = fopen("hello", "w+");  6         if(fp == NULL){  7                 perror("fopen");  8                 return 1;  9         } 10  11         char *p = NULL; 12         char *buff = "hello boy!"; 13  14         int ret = fputs(buff, fp); //把内容写入文件中 15         if(ret < 0){ 16                 perror("fputs"); 17                 return 1; 18         } 19  20         fseek(fp, 0, SEEK_SET);//将文件指针指向头，因为在赋值时已经指向了最后 21  22         unsigned char arr[1024] = {0}; //这个数组是用来存文件里的内容的 23         p = fgets(arr, 1024, fp); 24         if(p == NULL){ 25                 perror("fgets"); 26                 return 1; 27         } 28         printf("%s \n", arr); 29 }