A structure is a composite data type in C programming that enables combining several data types under one name. A structure inside a structure is also called a nested structure. In this article, we will learn how to declare a structure inside a structure in C++.

Declare a Struct Inside a Struct in C

To declare a structure inside a structure, we need to first define the inner structure(the structure that we want to nest inside another structure) and then define the outer struct and include the inner struct as a member using the below syntax:

Syntax to Declare Nested Structure

struct innerStructName {
     //define inner structure
};

struct outerStructName {
    struct innerStructName st; // inner struct as Direct member
};

We can also declare it directly inside the parent structure:

struct outerStructName {
    struct innerStructName {
       //define inner structure
    };
};

C Program to Declare Struct Inside a Struct

The below program demonstrates how we can declare a nested structure and use it in C.

Outer Data: 0
Inner Char: X
Inner Float: 5.14