Character-by-character

The simplest Input-Output operations are performed at the character level using getchar() and putchar():

int getchar(void)

and

int putchar(int)

• getchar() returns the next character from the standard input stream as an object with type int;
• putchar() takes a single character argument and outputs it on the standard output stream (returns the character written, or EOF to indicate an error).

    #include <stdio.h>

    /* Copy standard input to standard output : */

    main() {

        int c;

        c = getchar();

        /* while not reached end-of-file on input : */
        while (c != EOF) {
            putchar(c);       /* ignore possible errors */
            c = getchar();
          }
      }

• <stdio.h> includes the definitions of these functions and the value of the constant EOF which is returned when end-of-file is encountered.
  
  
• N.B. int not char is used since it must hold the value associated with EOF as well as all valid character values.