C语言库rewind()函数

#include <stdio.h>

int main () {
   char str[] = "This is yiibai.com";
   file *fp;
   int ch;

   /* First let's write some content in the file */
   fp = fopen( "file.txt" , "w" );
   fwrite(str , 1 , sizeof(str) , fp );
   fclose(fp);

   fp = fopen( "file.txt" , "r" );
   while(1) {
      ch = fgetc(fp);
      if( feof(fp) ) {
         break ;
      }
      printf("%c", ch);
   }

   rewind(fp);
   printf("\n");
   while(1) {
      ch = fgetc(fp);
      if( feof(fp) ) {
         break ;
      }
      printf("%c", ch);
   }

   fclose(fp);
   return(0);
}