cppreference.com > Standard C I/O > putc putc Syntax:
      #include <stdio.h>
      int putc( int ch, FILE *stream );
The putc() function writes the character ch to stream. The return value is the character written, or EOF if there is an error. For example:
       char ch;
       FILE *input, *output;
       input = fopen( "tmp.c", "r" );
       output = fopen( "tmpCopy.c", "w" );
       ch = getc( input );
       while( ch != EOF ) {
         putc( ch, output );
         ch = getc( input );
       }
       fclose( input );
       fclose( output );
generates a copy of the file tmp.c called tmpCopy.c. Related topics: feof fflush fgetc fputc getc getchar putchar puts