enum to string

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enum to string

使用 switch case

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enum EValue { KZero, KOne, KTwo };

const char* ToString(EValue value)
{
	switch (value) {
	case KZero:
		return "Zero";
	case KOne:
		return "One";
	case KTwo:
		return "Two";
	}
	return "Not Defined";
}

使用陣列索引進行查表

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enum EValue { KZero, KOne, KTwo };

const char* ToString(EValue value)
{
	static char *table[] = { "Zero", "One", "Two" };
	return table[value];
}

使用 X Macro 來實作陣列查表

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#define VALUE_TABLE \
	X(KZero, "Zero") \
	X(KOne, "One") \
	X(KTwo, "Two")

#define X(a, b) a,
enum EValue { VALUE_TABLE };
#undef X

const char* ToString(EValue value)
{
#define X(a, b) b,
	static char *table[] = { VALUE_TABLE };
#undef X
	return table[value];
}
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#define FOREACH_FRUIT(FRUIT) \
        FRUIT(apple)   \
        FRUIT(orange)  \
        FRUIT(grape)   \
        FRUIT(banana)  \

#define GENERATE_ENUM(ENUM) ENUM,
#define GENERATE_STRING(STRING) #STRING,

enum FRUIT_ENUM {
    FOREACH_FRUIT(GENERATE_ENUM)
};

static const char *FRUIT_STRING[] = {
    FOREACH_FRUIT(GENERATE_STRING)
};

// After the preprocessor gets done, you'll have:
// enum FRUIT_ENUM {
//     apple, orange, grape, banana,
// };

// static const char *FRUIT_STRING[] = {
//     "apple", "orange", "grape", "banana",
// };
printf("enum apple as a string: %s\n",FRUIT_STRING[apple]);

advanced macro

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enum fruit                                                                   
{
    APPLE = 0, 
    ORANGE, 
    GRAPE,
    BANANA,
    /* etc. */
    FRUIT_MAX
};   

const char * const fruit_str[] =
{
    [BANANA] = "banana",
    [ORANGE] = "orange",
    [GRAPE]  = "grape",
    [APPLE]  = "apple",
    /* etc. */  
};

printf("enum apple as a string: %s\n", fruit_str[APPLE]);

reference