C/stdio.h/fflush

    
//Header:       #include <stdio.h>  
//Declaration:  int fflush(FILE *stream); 
//Return:       0 on success or EOF on error. 
  #include <stdio.h>
  #include <stdlib.h>
  int main(void){
     FILE *fp;
     if((fp=fopen("test", "rb"))==NULL) {
        printf("Cannot open file.\n");
        exit(1);
     }
      char ch = "C";
      int i;
      for(i=0; i<5; i++) {
        fwrite(ch, sizeof(ch), 1, fp);
        fflush(fp);
      }
      fclose(fp);
      return 0;
  }