Question

How to access an individual member of a struct without using the name of the member in C

Answer 1

#include <stdio.h>

typedef struct my_struct {
    int member1;
    char member2;
    short member3;
    float member4;
} my_struct;

int main() {
    my_struct st;
    
    st.member3 = 578;
    short m3 = *( (short*) ( (char*)&st + 6) );
    printf("%d\n", m3);

    st.member3 = 1092;
    m3 = *( (short*) ( (char*)&st + sizeof(int) + sizeof(char) + 1) );
    printf("%d\n", m3);

    *( (float*) ( (char*)&st + 8 ) ) = 3.14f;
    printf("%.2f\n", st.member4);
    
    *( (float*) ( (char*)&st + sizeof(int) + sizeof(char) + sizeof(short) + 1) ) = 0.07f;
    printf("%.2f\n", st.member4);
    
    return 0;
}




/*
run:

578
1092
3.14
0.07

*/

 

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