如何编写一个宏来遍历变量列表并返回缺少的变量

#include <stdio.h>

#define checkMissingVariables(...) \
    do { \
        const char* missingVariables = ""; \
        const int numVariables = sizeof((int[]){__VA_ARGS__}) / sizeof(int); \
        \
        for (int i = 0; i < numVariables; i++) { \
            const char* variableName = #__VA_ARGS__[i]; \
            \
            #ifdef variableName \
                printf("%s is defined\n", variableName); \
            #else \
                printf("%s is missing\n", variableName); \
                missingVariables = strcat(missingVariables, variableName); \
                missingVariables = strcat(missingVariables, ", "); \
            #endif \
        } \
        \
        if (strlen(missingVariables) > 0) { \
            missingVariables[strlen(missingVariables) - 2] = '\0'; \
            printf("Missing variables: %s\n", missingVariables); \
        } else { \
            printf("No missing variables\n"); \
        } \
    } while(0)

int main() {
    int var1 = 1;
    int var3 = 3;
    
    checkMissingVariables(var1, var2, var3);
    
    return 0;
}

var1 is defined
var2 is missing
var3 is defined
Missing variables: var2