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How to Declare a Struct Member Inside a Union in C?

Last Updated : 23 Jul, 2025

A union contains different types of variables as its members and all these members share a memory location. In this article, we will learn how to declare and access the struct member inside a union in C++.

Structure Inside Union in C

To declare a structure inside a union we can use the below syntax:

Syntax to Declare Structure Inside Union in C

union unionName {
 struct structName structVar; // Struct as a member of the union
};

Here, structName is the name of the structure defined somewhere before the union declaration.

We can also declare the structure member directly inside the union as shown:

union unionName {
struct structName {
struct_member1;
struct_member2;
}structVar; // Struct as a member of the union
};

C Program to Declare Structure Inside Union

The below program demonstrates how we can declare a structure inside a union in C.


Output
Number: 42
Character: A
Point: (10, 20)


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