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  1.   #include <stddef.h>
  2.   #include <ctype.h>
  3.   #include <stdlib.h>
  4.   #include <string.h>
  5.   #include <stdio.h>
  6.  
  7.   static int in_set(
  8.       register const int c,
  9.       register const char * chars
  10.     ) {
  11.       register int test;
  12.  
  13.       while ((test = *chars)) {
  14.           if (c == test)
  15.             return 1;
  16.           ++chars;
  17.           continue;
  18.         }
  19.       return 0;
  20.     }
  21.  
  22.   char * rstrip(
  23.       register const char * const string,
  24.       register const char * const chars
  25.     ) {
  26.       register char c;
  27.       register const char * cur_pos = string;
  28.       register const char * one_past_end = string + 1;
  29.       register ptrdiff_t diff;
  30.       register char * copy;
  31.  
  32.       if (!chars) {
  33.           while ((c = *cur_pos)) {
  34.               if (!isspace(c))
  35.                 one_past_end = cur_pos + 2;
  36.               ++cur_pos;
  37.               continue;
  38.             }
  39.         } else {
  40.           while ((c = *cur_pos)) {
  41.               if (!in_set(c, chars))
  42.                 one_past_end = cur_pos + 2;
  43.               ++cur_pos;
  44.               continue;
  45.             }
  46.         }
  47.       diff = one_past_end - string;
  48.       copy = malloc(diff);
  49.       if (!copy)
  50.         return NULL;
  51.  
  52.       --diff;
  53.       copy[diff] = '\0';
  54.       return memcpy(copy, string, diff);
  55.     }
  56.  
  57.   int main(void) {
  58.       char * tests[] = {
  59.           "",
  60.           " ",
  61.           "        ",
  62.           "f",
  63.           " f",
  64.           "   f",
  65.           "   f   ",
  66.           "   f ",
  67.           "f   ",
  68.           "f ",
  69.           "foo bar   baz",
  70.           " foo bar   baz",
  71.           "                  foo bar   baz",
  72.           "                  foo bar   baz                 ",
  73.           " foo bar   baz                ",
  74.           "foo bar   baz                ",
  75.           "foo bar   baz ",
  76.           "mississippi",
  77.         };
  78.       int i;
  79.       char * stripped;
  80.  
  81.       for (i = 0; i < (sizeof tests / sizeof *tests) - 1; ++i) {
  82.           stripped = rstrip(tests[i], NULL);
  83.           if (stripped)
  84.             printf("[%s]\n", stripped);
  85.           free(stripped);
  86.           continue;
  87.         }
  88.       stripped = rstrip(tests[i], "ipz");
  89.       if (stripped)
  90.         printf("[%s]\n", stripped);
  91.       free(stripped);
  92.  
  93.       return EXIT_SUCCESS;
  94.     }
  95.  
Success #stdin #stdout 0.02s 1852KB
comments (?)
stdin
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Standard input is empty
stdout
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[]
[]
[]
[f]
[ f]
[   f]
[   f]
[   f]
[f]
[f]
[foo bar   baz]
[ foo bar   baz]
[                  foo bar   baz]
[                  foo bar   baz]
[ foo bar   baz]
[foo bar   baz]
[foo bar   baz]
[mississ]
https://ideone.com/lp5mj
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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