#include <stdio.h>
#include <iostream>
#include <vector>
#include <string.h>
 
#define MACRO_GET_1(str, i) \
    (sizeof(str) > (i) ? str[(i)] : 0)
 
#define MACRO_GET_4(str, i) \
    MACRO_GET_1(str, i+0),  \
    MACRO_GET_1(str, i+1),  \
    MACRO_GET_1(str, i+2),  \
    MACRO_GET_1(str, i+3)
 
#define MACRO_GET_STR(str) MACRO_GET_4(str, 0)
 
struct mystruct {
  char foo[4];  
};
 
int main() {
	mystruct obj{ MACRO_GET_STR("abcd") };
    const char* str = "abcd";
    std::cout << memcmp(obj.foo, str, 4); // 0
 
	return 0;
}

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