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  1. #include <stdlib.h>
  2. #include <stdio.h>
  3. #include <string.h>
  4.  
  5. // int alpha_range(char c) { return 0 != strchr("abcdefghijklmnopqrstuvwxyz", c); }
  6. // int digit_range(char c) { return 0 != strchr("0123456789", c); }
  7.  
  8. int alpha_range(char c) { return (c>='a') && (c<='z'); }
  9. int digit_range(char c) { return (c>='0') && (c<='9'); }
  10.  
  11. char* expand(const char* s)
  12. {
  13.     char buf[2048];
  14.  
  15.     const char* in  = s;
  16.           char* out = buf;
  17.  
  18.     // parser state
  19.     int (*predicate)(char) = 0; // either: NULL (free state), alpha_range (in alphabetic range), digit_range (in digit range)
  20.     char lower=0,upper=0;       // tracks lower and upper bound of character ranges in the range parsing states
  21.  
  22.     // init
  23.     *out = 0;
  24.  
  25.     while (*in)
  26.     {
  27.         if (!predicate)
  28.         {
  29.             // free parsing state
  30.             if (alpha_range(*in) && (in[1] == '-') && alpha_range(in[2]))
  31.             {
  32.                 lower = upper = *in++;
  33.                 predicate = &alpha_range;
  34.             }
  35.             else if (digit_range(*in) && (in[1] == '-') && digit_range(in[2]))
  36.             {
  37.                 lower = upper = *in++;
  38.                 predicate = &digit_range;
  39.             } 
  40.             else *out++ = *in;
  41.         } else
  42.         { 
  43.             // in a range
  44.             if (*in < lower) lower = *in;
  45.             if (*in > upper) upper = *in;
  46.  
  47.             if (in[1] == '-' && predicate(in[2])) 
  48.                 in++; // more coming
  49.             else
  50.             {
  51.                 // end of range mode, dump expansion
  52.                 char c;
  53.                 for (c=lower; c<=upper; *out++ = c++);
  54.                 predicate = 0;
  55.             }
  56.         }
  57.         in++;
  58.     }
  59.  
  60.     *out = 0; // null-terminate buf
  61.     return strdup(buf);
  62. }
  63.  
  64. void dotest(const char* const input)
  65. {
  66.     char* ex = expand(input);
  67.     printf("input : '%s'\noutput: '%s'\n\n", input, ex);
  68.  
  69.     if (ex)
  70.         free(ex);
  71. }
  72.  
  73. int main (int argc, char *argv[])
  74. {
  75.     dotest("a-z or 0-9 or a-b-c or a-z0-9"); // from the original post
  76.     dotest("This is some e-z test in 5-7 steps; this works: a-b-c. This works too: b-k-c-e. Likewise 8-4-6"); // from my C++ answer
  77.     dotest("-x-s a-9 9- a-k-9 9-a-c-7-3"); // assorted torture tests
  78.  
  79.     return 0;
  80. }
  81.  
Success #stdin #stdout 0s 1852KB
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stdin
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Standard input is empty
stdout
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input : 'a-z or 0-9 or a-b-c or a-z0-9'
output: 'abcdefghijklmnopqrstuvwxyz or 0123456789 or abc or abcdefghijklmnopqrstuvwxyz0123456789'

input : 'This is some e-z test in 5-7 steps; this works: a-b-c. This works too: b-k-c-e. Likewise 8-4-6'
output: 'This is some efghijklmnopqrstuvwxyz test in 567 steps; this works: abc. This works too: bcdefghijk. Likewise 45678'

input : '-x-s a-9 9- a-k-9 9-a-c-7-3'
output: '-stuvwx a-9 9- abcdefghijk-9 9-abc-34567'
https://ideone.com/sXM7b
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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