C语言读取文件中每一行的前四个字符[原创]

//读取文件中每一行的前四个字符
//memcpy与strncpy的功能差不多一样
//要调用上面两个函数要先引入库string.h
//使用malloc要调用stdlib.h库
＃i nclude
＃i nclude
＃i nclude
int main()
{
 char *sfrom="1234567890";
 char *sto=(char*) malloc(10);
 memcpy(sto,sfrom,3);
 printf(sto);
 strncpy(sto,sfrom,3);
 printf("\n");
 printf(sto);
 printf("\n");

 FILE *fp=fopen("du.txt","r");
 char ln[100];
 char *out=(char*) malloc(10);
 while(!feof(fp))
 {
  fgets(ln,1024,fp);
  memcpy(out,ln,4);
  printf(out);
  printf("\n");

 }
 return 0;
}