upe(6.2, 6.3): Program arguments and File access

/* upe(6.2): Program argument: vis version 2
upe(6.3): File access: vis version 3
   created on Mar 28, 2011
   */

/* vis: make funny characters visible (version 3) */

#include    "stdio.h"
#include    "ctype.h"
int strip = 0;   /* 1 => discard special characters */

int main(int argc, char *argv[])
{
    int i;
    FILE *fp;

    while(argc > 1 && argv[1][0] == '-') {
        switch (argv[1][1]) {
            case 's':    /* -s: strip funny chars */
                strip = 1;
                break;
            default:
                fprintf(stderr, "%s: unknown arg %s\n",
                            argv[0], argv[1]);
                exit(1);
        }
        argc--;
        argv++;
    }
    if (argc == 1)
      vis(stdin);
    else
      for (i = 1; i < argc; i++)
        if ((fp=fopen(argv[i], "r")) == NULL) {
            fprintf(stderr, "%s: can't open %s\n",
                        argv[0], argv[i]);
            exit(1);
        } else {
            vis(fp);
            fclose(fp);
        }
    return 0;
}


/* vis: make chars visible in FILE *fp */
vis(FILE *fp)
{
    int c;

    while ((c = getc(fp)) != EOF)
      if (isascii(c) &&
                  (isprint(c) || c=='\n' || c=='\t' || c==' '))
        putchar(c); //put on terminal
      else if (!strip)
        printf("\\%03o", c);
}