k&r(7.5, 7.6): File Access, Error Handling

/* k&r(7.5): File Access, Error Handling
   created on mar 27, 2011
   */

#include    "stdio.h"

/* cat: concatenate files, version 2 */
main(int argc, char *argv[])
{
    FILE *fp;
    void filecopy(FILE *, FILE *);
    char *prog = argv[0];   /* program name for errors */

    if (argc == 1)  /* no args; copy standard input */
      filecopy(stdin, stdout);
    else
      while (--argc > 0)
        if ((fp = fopen(*++argv, "r")) == NULL) {
            fprintf (stderr, "%s: can't open %s\n", prog, *argv);
            exit(1);
        } else {
            filecopy(fp, stdout);
            fclose(fp);
        }
    if (ferror(stdout)) {
        fprintf(stderr, "%s: error writing stdout\n", prog);
        exit(2);
    }
    exit(0);
}

/* filecopy: copy file ifp to file ofp */
void filecopy(FILE *ifp, FILE *ofp)
{
    int c;

    while ((c = getc(ifp)) != EOF)
      putc(c, ofp);
}