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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <stdlib.h>
  4.  
  5. typedef struct Binding
  6. {
  7.   int* pIntVar;
  8.   const char* IntVarName;
  9.   struct Binding* pNext;
  10. } Binding;
  11.  
  12. Binding* Bindings = NULL;
  13.  
  14. void BindVar(const char* IntVarName, int* pIntVar)
  15. {
  16.   Binding* b;
  17.   if ((b = malloc(sizeof(Binding))) != NULL)
  18.   {
  19.     b->IntVarName = IntVarName;
  20.     b->pIntVar = pIntVar;
  21.     b->pNext = NULL;
  22.     if (Bindings == NULL)
  23.     {
  24.       Bindings = b;
  25.     }
  26.     else
  27.     {
  28.       Binding* bs = Bindings;
  29.       while (bs->pNext != NULL)
  30.       {
  31.         bs = bs->pNext;
  32.       }
  33.       bs->pNext = b;
  34.     }
  35.   }
  36.   else
  37.   {
  38.     fprintf(stderr, "malloc() failed\n");
  39.     exit(-1);
  40.   }
  41. }
  42.  
  43. int* GetVarPtr(const char* IntVarName)
  44. {
  45.   Binding* bs = Bindings;
  46.   while (bs != NULL)
  47.   {
  48.     if (!strcmp(bs->IntVarName, IntVarName))
  49.     {
  50.       return bs->pIntVar;
  51.     }
  52.     bs = bs->pNext;
  53.   }
  54.   fprintf(stderr, "variable \"%s\" not bound yet!\n", IntVarName);
  55.   exit(-1);
  56. }
  57.  
  58. int main(void)
  59. {
  60.   int ABC = 111, DEF = 222, XYZ = 333;
  61.   const char* varName = NULL;
  62.  
  63.   BindVar("ABC", &ABC);
  64.   BindVar("DEF", &DEF);
  65.   BindVar("XYZ", &XYZ);
  66.  
  67.   printf("variable \"%s\" = %d\n", "ABC", *GetVarPtr("ABC"));
  68.   printf("variable \"%s\" = %d\n", "DEF", *GetVarPtr("DEF"));
  69.   printf("variable \"%s\" = %d\n", "XYZ", *GetVarPtr("XYZ"));
  70.  
  71.   // Pick a variable randomly by name
  72.  
  73.   switch (rand() % 3)
  74.   {
  75.   case 0: varName = "ABC"; break;
  76.   case 1: varName = "DEF"; break;
  77.   case 2: varName = "XYZ"; break;
  78.   }
  79.  
  80.   printf("variable \"%s\" (selected randomly) = %d\n", varName, *GetVarPtr(varName));
  81.  
  82.   // Hide the pointer stuff behind this macro:
  83. #define VARIABLE(NAME) (*GetVarPtr(NAME))
  84.  
  85.   VARIABLE("ABC") = 1;
  86.   VARIABLE("DEF") = 2;
  87.   VARIABLE("XYZ") = 3;
  88.  
  89.   printf("variable \"%s\" = %d\n", "ABC", VARIABLE("ABC"));
  90.   printf("variable \"%s\" = %d\n", "DEF", VARIABLE("DEF"));
  91.   printf("variable \"%s\" = %d\n", "XYZ", VARIABLE("XYZ"));
  92.  
  93.   return 0;
  94. }
  95.  
Success #stdin #stdout 0.01s 1808KB
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stdin
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Standard input is empty
stdout
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variable "ABC" = 111
variable "DEF" = 222
variable "XYZ" = 333
variable "DEF" (selected randomly) = 222
variable "ABC" = 1
variable "DEF" = 2
variable "XYZ" = 3
https://ideone.com/7Fhag
language:
C99 (gcc 8.3)
created:
11 years ago
visibility:
public

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