SAS/C Library Reference, Vol. 1

putc -- Write a Character to a File

SYNOPSIS

 #include <stdio.h>

 int putc(int c, FILE *f);

DESCRIPTION

putc writes a single character c to the stream associated with the FILE object addressed by f.

RETURN VALUE

putc returns the output character or EOF if an error occurs.

IMPLEMENTATION

putc is implemented as a built-in function. A subroutine call is executed only if no output buffer is allocated, the output buffer is full, or a control character is written.

The code generated for putc normally includes tests for a NULL FILE pointer and for a stream that failed to open. If you define the symbol _FASTIO using #define or the DEFine compiler option before including <stdio.h>, no code is generated for these checks. This enables you to improve the performance of debugged programs that use putc.

EXAMPLE

This example copies characters from an input file to an output file, and it writes a blank after each period:

  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>

  #define _FASTIO  /* Improve getc/putc performance. */

  main()
  {
     FILE *infile, *outfile;
     char filename[60];
     int c;

     puts("Enter the name of your input file:");
     memcpy(filename, "tso:", 4);
     gets(filename+4);
     infile = fopen(filename, "r");
     if (!infile){
        puts("Failed to open input file.");
        exit(EXIT_FAILURE);
     }
     puts("Enter the name of your output file:");
     memcpy(filename, "tso:", 4);
     gets(filename+4);
     outfile = fopen(filename, "w");
     if (!outfile){
        puts("Failed to open output file.");
        exit(EXIT_FAILURE);
     }
     for (;;){
        c = getc(infile);
        if (c == EOF) break;
        c = putc(c, outfile);
        if (c == '.') putc(' ', outfile);
     }

     fclose(infile);
     fclose(outfile);
  }

RELATED FUNCTIONS

fputc, putchar