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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4.  
  5. enum VTYPE {VSTRING, VINT, VFLOAT};
  6. typedef enum VTYPE vtype;
  7. struct Value {
  8.    vtype typ;
  9.    /*
  10.    type=1  ==> get vstring
  11.    type=2  ==> get int
  12.    type=3  ==> get float
  13.    */
  14.    union {
  15.    	char *vstring;
  16.    	int   vint;
  17.    	float  vfloat;
  18.    };
  19. };
  20.  
  21. void clear(struct Value* vall){
  22.    if (vall->typ == VSTRING){
  23.       free(vall->vstring);
  24.    }
  25.    memset(vall, 0, sizeof(*vall));
  26. }
  27.  
  28. void print_value(struct Value *v)
  29. {
  30. 	static const char *types[] = {"VSTRING", "VINT", "VFLOAT"};
  31. 	printf( "ValueType : %s\n", v->typ >= 0 && v->typ < 3 ? types[v->typ] : "ERROR");
  32. 	if (VSTRING == v->typ) {
  33.     	printf( "ValueString : %s\n", v->vstring);
  34. 	}
  35. 	else if (VINT == v->typ) {
  36.     	printf( "ValueInt : %d\n", v->vint);
  37. 	}
  38. 	else if (VFLOAT == v->typ) {
  39.     	printf( "ValueFloat : %f\n", v->vfloat);
  40. 	}
  41. }
  42.  
  43. void copy_value(struct Value *source, struct Value *dest) {
  44. 	if (VSTRING == source->typ) {
  45.     	dest->vstring = malloc(strlen(source->vstring) + 1);
  46.     	strcpy(dest->vstring, source->vstring);
  47. 	}
  48. 	else if (VINT == source->typ) {
  49.     	dest->vint = source->vint;
  50. 	}
  51. 	else if (VFLOAT == source->typ) {
  52.     	dest->vfloat = source->vfloat;
  53. 	}
  54. 	dest->typ = source->typ;
  55. }
  56.  
  57. int main()
  58. {
  59. 	const char *msg = "C Programming/may this a very big utf-8 string!";
  60.    struct Value v;
  61.    /////////////////////////////////////////////
  62.    v.typ=VSTRING;
  63.    v.vstring = malloc(strlen(msg) + 1);
  64.    strcpy(v.vstring, msg);
  65.    print_value(&v);
  66.  
  67.  
  68. 	struct Value copy;
  69. 	copy_value(&v, &copy);
  70. 	print_value(&copy);
  71.    clear(&copy);
  72.    copy.typ=VINT;
  73.    copy.vint=5;
  74.    print_value(&copy);
  75.  
  76.    clear(&v);
  77. }
  78.  
Success #stdin #stdout 0s 10320KB
comments (?)
stdin 
Standard input is empty
stdout 
ValueType : VSTRING
ValueString : C Programming/may this a very big utf-8 string!
ValueType : VSTRING
ValueString : C Programming/may this a very big utf-8 string!
ValueType : VINT
ValueInt : 5
https://ideone.com/ecy3qa
language:
C (gcc 8.3)
created:
8 years ago
visibility:
public

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