C Structures and Unions

A struct groups variables of different types under one name.

#include <stdio.h>
#include <string.h>

struct Student {
    int roll;
    char name[20];
    float cgpa;
};

int main() {
    struct Student s1 = {1, "Asha", 8.9};
    struct Student *p = &s1;
    strcpy(p->name, "Asha K");          // -> for pointer access
    printf("%d %s %.1f\n", s1.roll, s1.name, p->cgpa);
    return 0;
}

1 Asha K 8.9

Structure vs Union

Structure	Union
Each member has its own memory	All members share the same memory
Size ≥ sum of members (plus padding)	Size = largest member
All members usable at once	Only one member valid at a time

union Data { int i; float f; char c; };
printf("%zu\n", sizeof(union Data));

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