commands/fold/fold.c

   1 /* fold - folds long lines              Author: Terrence W. Holm */
   2
   3 /*  Usage:  fold  [ -width ]  [ file ... ]  */
   4
   5 #include <stdlib.h>
   6 #include <stdio.h>
   7
   8 #define  TAB            8
   9 #define  DEFAULT_WIDTH  80
  10
  11 int column = 0;                 /* Current column, retained between files  */
  12
  13 int main(int argc, char **argv);
  14 void Fold(FILE *f, int width);
  15
  16 int main(argc, argv)
  17 int argc;
  18 char *argv[];
  19 {
  20   int width = DEFAULT_WIDTH;
  21   int i;
  22   FILE *f;
  23
  24   if (argc > 1 && argv[1][0] == '-') {
  25         if ((width = atoi(&argv[1][1])) <= 0) {
  26                 fprintf(stderr, "Bad number for fold\n");
  27                 exit(1);
  28         }
  29         --argc;
  30         ++argv;
  31   }
  32   if (argc == 1)
  33         Fold(stdin, width);
  34   else {
  35         for (i = 1; i < argc; ++i) {
  36                 if ((f = fopen(argv[i], "r")) == NULL) {
  37                         perror(argv[i]);
  38                         exit(1);
  39                 }
  40                 Fold(f, width);
  41                 fclose(f);
  42         }
  43   }
  44   return(0);
  45 }
  46
  47
  48 void Fold(f, width)
  49 FILE *f;
  50 int width;
  51 {
  52   int c;
  53
  54   while ((c = getc(f)) != EOF) {
  55         if (c == '\t')
  56                 column = (column / TAB + 1) * TAB;
  57         else if (c == '\b')
  58                 column = column > 0 ? column - 1 : 0;
  59         else if (c == '\n' || c == '\r')
  60                 column = 0;
  61         else
  62                 ++column;
  63
  64         if (column > width) {
  65                 putchar('\n');
  66                 column = c == '\t' ? TAB : 1;
  67         }
  68         putchar(c);
  69   }
  70 }