C/stdio.h/fprintf

    
//Header:       #include <stdio.h>  
//Declaration:  int fprintf(FILE *stream, const char *format, ...); 
//Return:       returns the number of characters printed on 
                success or a negative number on failure. 


  
  #include <stdio.h>
  #include <stdlib.h>
  int main(void)
  {
    FILE *fp;
    if((fp=fopen("test", "wb"))==NULL) {
      printf("Cannot open file.\n");
      exit(1);
    }
    //The format control string are identical to those in printf();
    fprintf(fp, "this is a test %d %f", 10, 20.01);
    fclose(fp);
    return 0;
  }