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  1. // Convert a signed long integer to English text. (2.00)
  2. // @see dwYRr9
  3.  
  4. #include <stdlib.h>
  5. #include <limits.h>
  6. #include <string.h>
  7. #include <stdio.h>
  8. #include <time.h>
  9. #include <assert.h>
  10.  
  11. //
  12. // Utility.
  13. //
  14.  
  15. struct astring {
  16.     char first[288], * last;
  17. };
  18.  
  19. char* stpcpy_(char* s, const char* t)
  20. {
  21.     size_t n = strlen(t);
  22.     memcpy(s, t, n + 1);
  23.     return s + n;
  24. }
  25.  
  26. struct astring* astring_append(struct astring* s, const char* t)
  27. {
  28.     s->last = stpcpy_(s->last, t);
  29.     return s;
  30. }
  31.  
  32. //
  33. // Convert.
  34. //
  35.  
  36. struct astring* textnumber_detail(int n, struct astring* result)
  37. {
  38.     assert(1 <= n && n <= 999);
  39.  
  40.     static const char* ones[] = {
  41.         "",
  42.         "one",
  43.         "two",
  44.         "three",
  45.         "four",
  46.         "five",
  47.         "six",
  48.         "seven",
  49.         "eight",
  50.         "nine"
  51.     };
  52.  
  53.     static const char* teens[] = {
  54.         "ten",
  55.         "eleven",
  56.         "twelve",
  57.         "thirteen",
  58.         "fourteen",
  59.         "fifteen",
  60.         "sixteen",
  61.         "seventeen",
  62.         "eighteen",
  63.         "nineteen"
  64.     };
  65.  
  66.     static const char* tens[] = {
  67.         "",
  68.         "",
  69.         "twenty",
  70.         "thirty",
  71.         "forty",
  72.         "fifty",
  73.         "sixty",
  74.         "seventy",
  75.         "eighty",
  76.         "ninety"
  77.     };
  78.  
  79.     // Hundreds.
  80.  
  81.     if (n >= 100)
  82.     {
  83.         astring_append(result, ones[n / 100 % 10]);
  84.         astring_append(result, " hundred");
  85.         n %= 100;
  86.         if (n != 0)
  87.             astring_append(result, " and ");
  88.     }
  89.  
  90.     // Tens and ones.
  91.  
  92.     if (n < 10)
  93.     {
  94.         astring_append(result, ones[n]);
  95.     }
  96.     else if (n < 20)
  97.     {
  98.         astring_append(result, teens[n % 10]);
  99.     }
  100.     else
  101.     {
  102.         astring_append(result, tens[n / 10]);
  103.         if (n % 10)
  104.         {
  105.             astring_append(result, "-");
  106.             astring_append(result, ones[n % 10]);
  107.         }
  108.     }
  109.     return result;
  110. }
  111.  
  112. const char* textnumber(long int n)
  113. {
  114.     assert(n > LONG_MIN || LONG_MIN + LONG_MAX == 0);
  115.  
  116.     static const char* base[] = {
  117.         "",
  118.         " thousand",
  119.         " million",
  120.         " billion",
  121.         " trillion",
  122.         " quadrillion",
  123.         " quintillion"
  124.     };
  125.  
  126.     static _Thread_local struct astring result[1];
  127.     result->last = result->first;
  128.  
  129.     // Zero.
  130.  
  131.     if (n == 0)
  132.     {
  133.         astring_append(result, "zero");
  134.         return result->first;
  135.     }
  136.  
  137.     // Negative.
  138.  
  139.     if (n < 0)
  140.     {
  141.         astring_append(result, "minus ");
  142.         n = -n;
  143.     }
  144.  
  145.     // Log base 1000.
  146.  
  147.     long int k = 1;
  148.     int j = 0;
  149.     for (long int i = n; i >= 1000; i /= 1000)
  150.     {
  151.         j += 1;
  152.         k *= 1000;
  153.     }
  154.  
  155.     // Powers of 1000.
  156.  
  157.     for (int i = j; i >= 0; i--)
  158.     {
  159.         long int m = n / k % 1000;
  160.         if (m != 0)
  161.         {
  162.             astring_append(textnumber_detail(m, result), base[i]);
  163.             if (n % k != 0)
  164.                 astring_append(result, ", ");
  165.             else break;
  166.         }
  167.         k /= 1000;
  168.     }
  169.     return result->first;
  170. }
  171.  
  172. //
  173. // Show.
  174. //
  175.  
  176. int main(int argc, char* argv[])
  177. {
  178.     printf("%d\n%s\n\n", 0, textnumber(0));
  179.     printf("%d\n%s\n\n", -1, textnumber(-1));
  180.     printf("%d\n%s\n\n", 1000000, textnumber(1000000));
  181.     printf("%d\n%s\n\n", 1000003, textnumber(1000003));
  182.     printf("%d\n%s\n\n", 1002003, textnumber(1002003));
  183.     printf("%ld\n%s\n\n", LONG_MAX, textnumber(LONG_MAX));
  184.  
  185.     srand(time(0));
  186.     for (int i = 0; i < 5; i++)
  187.     {
  188.         int x = rand() % 21 - 10;
  189.         printf("%d\n%s\n\n", x, textnumber(x));
  190.     }
  191.     for (int i = 0; i < 5; i++)
  192.     {
  193.         int x = rand() % 201 - 100;
  194.         printf("%d\n%s\n\n", x, textnumber(x));
  195.     }
  196.     for (int i = 0; i < 5; i++)
  197.     {
  198.         int x = rand() % 2001 - 1000;
  199.         printf("%d\n%s\n\n", x, textnumber(x));
  200.     }
  201.     for (int i = 0; i < 5; i++)
  202.     {
  203.         int x = rand() - rand();
  204.         printf("%d\n%s\n\n", x, textnumber(x));
  205.     }
  206.     return 0;
  207. }
Success #stdin #stdout 0s 5280KB
comments (?)
stdin 
Standard input is empty
stdout 
0
zero

-1
minus one

1000000
one million

1000003
one million, three

1002003
one million, two thousand, three

9223372036854775807
nine quintillion, two hundred and twenty-three quadrillion, three hundred and seventy-two trillion, thirty-six billion, eight hundred and fifty-four million, seven hundred and seventy-five thousand, eight hundred and seven

-2
minus two

5
five

0
zero

-8
minus eight

7
seven

61
sixty-one

-10
minus ten

-22
minus twenty-two

-84
minus eighty-four

-60
minus sixty

906
nine hundred and six

231
two hundred and thirty-one

-574
minus five hundred and seventy-four

770
seven hundred and seventy

533
five hundred and thirty-three

-548126886
minus five hundred and forty-eight million, one hundred and twenty-six thousand, eight hundred and eighty-six

-623571431
minus six hundred and twenty-three million, five hundred and seventy-one thousand, four hundred and thirty-one

-283271142
minus two hundred and eighty-three million, two hundred and seventy-one thousand, one hundred and forty-two

-607523002
minus six hundred and seven million, five hundred and twenty-three thousand, two

797028367
seven hundred and ninety-seven million, twenty-eight thousand, three hundred and sixty-seven
https://ideone.com/hPqLGR
language:
C (gcc 8.3)
created:
11 days ago
visibility:
public

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