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  1. #include <stddef.h>
  2. #include <stdio.h>
  3.  
  4. ///
  5. /// @brief Appends contents of array `from` to array `to`.
  6. /// @pre `limit` != `0`
  7. /// @note No operation is performed for a `limit` of `0`.
  8. /// @remarks Resulting array is NUL-terminated.
  9. /// @param [out] to      String to be written to.
  10. /// @param limit         Maximum number of bytes that string `to` can store, including NUL.
  11. /// @param [in] from     String to be copied from.
  12. /// @returns Size of resulting string (NUL not counted).
  13. ///
  14. size_t strscat(char *to, size_t limit, const char *from)
  15. {
  16.     size_t s=0;
  17.  
  18.     if (limit != 0)
  19.     {
  20.         while (to[s] != '\0')
  21.             ++s;
  22.  
  23.         for (size_t i=0; from[i] != '\0' && s < limit - 1; ++i, ++s)
  24.             to[s] = from[i];
  25.  
  26.         to[s] = '\0';
  27.     }
  28.  
  29.     return s;
  30. }
  31.  
  32. typedef struct
  33. {
  34.     char        *to;
  35.     size_t      limit;
  36.     const char  *from;
  37.     const char  *result;
  38.     size_t      retval;
  39. } test_t;
  40.  
  41. static size_t tests_failed;
  42.  
  43. static void run_test(test_t *t)
  44. {
  45.     size_t i=0;
  46.  
  47.     if (t->retval != strscat(t->to, t->limit, t->from))
  48.     {
  49.         ++tests_failed;
  50.         return;
  51.     }
  52.  
  53.     while (t->result[i] != '\0' || t->to[i] != '\0')
  54.         if (t->result[i] != t->to[i])
  55.         {
  56.             ++tests_failed;
  57.             break;
  58.         }
  59.         else
  60.             ++i;
  61. }
  62.  
  63. #define RUN_TEST(...)   run_test(&(test_t){__VA_ARGS__})
  64.  
  65. int main(void)
  66. {
  67.     RUN_TEST(
  68.         .to     = (char[15]){"The Cutty"},
  69.         .limit  = 15,
  70.         .from   = " Sark is a ship dry-docked in London.",
  71.         .result = "The Cutty Sark",
  72.         .retval = 14
  73.     );
  74.  
  75.     RUN_TEST(
  76.         .to     = (char[15]){"The Cutty"},
  77.         .limit  = 0,
  78.         .from   = "this won't get appended",
  79.         .result = "The Cutty",
  80.         .retval = 0
  81.     );
  82.  
  83.     RUN_TEST(
  84.         .to     = (char[15]){"The Cutty"},
  85.         .limit  = 15,
  86.         .from   = "!",
  87.         .result = "The Cutty!",
  88.         .retval = 10
  89.     );
  90.  
  91.     RUN_TEST(
  92.         .to     = (char[]){"The Cutty Sark"},
  93.         .limit  = 3,
  94.         .from   = "this shouldn't get appended",
  95.         .result = "The Cutty Sark",
  96.         .retval = 14
  97.     );
  98.  
  99.     RUN_TEST(
  100.         .to     = (char[]){"The Cutty Sark"},
  101.         .limit  = 1,
  102.         .from   = "this shouldn't get appended, either",
  103.         .result = "The Cutty Sark",
  104.         .retval = 14
  105.     );
  106.  
  107.     RUN_TEST(
  108.         .to     = (char[]){""},
  109.         .limit  = 1,
  110.         .from   = "this had better not get appended!",
  111.         .result = "",
  112.         .retval = 0
  113.     );
  114.  
  115.     (void)fprintf(stderr, "Number of tests failed: %zu.\n", tests_failed);
  116. }
Success #stdin #stdout #stderr 0s 2244KB
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stdin
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Standard input is empty
stdout
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Standard output is empty
stderr
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Number of tests failed: 0.
https://ideone.com/4Ls9PD
无名变量应用场合
language:
C99 (gcc 8.3)
created:
11 years ago
visibility:
public

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