C++ Structures: Understanding the Fundamentals and Usage


Structures play a vital role in C++ programming as they allow developers to define custom data types that can hold different types of variables. In this article, we will explore the concept of C++ structures, their syntax, usage, and differences compared to C structures. Whether you’re a beginner or an experienced programmer, this comprehensive guide will provide you with a solid foundation in understanding and utilizing C++ structures effectively.

1. What are Structures in C++?

In C++, a structure is a user-defined data type that allows the programmer to combine different types of variables under a single name. It provides a way to group related data elements together, making it easier to organize and manipulate data in a program. Structures are particularly useful when dealing with complex data structures, such as records, employee information, or student details.

2. Syntax and Declaration

To define a structure in C++, we use the struct keyword followed by the structure name and a pair of curly braces enclosing the member variables. Here’s the syntax:

struct StructureName {
    DataType member1;
    DataType member2;
    // ...

For example, let’s create a structure called “Person” with member variables for name and age:

struct Person {
    std::string name;
    int age;

3. Accessing Structure Members

To access the members of a structure, we use the dot (.) operator. Here’s an example that demonstrates accessing and modifying the members of the “Person” structure:

Person person1;
person1.name = "John";
person1.age = 25;

std::cout << "Name: " << person1.name << std::endl;
std::cout << "Age: " << person1.age << std::endl;

4. Defining Structures with Examples

Structures are incredibly versatile and can be used to represent various real-world entities. Let’s explore a few examples:

4.1 Employee Structure

struct Employee {
    std::string name;
    int employeeId;
    double salary;

4.2 Rectangle Structure

struct Rectangle {
    double length;
    double width;

5. Initializing Structures

Structures can be initialized during declaration or later using the assignment operator. Here are examples of both methods:

5.1 Initializing during Declaration

Person person2 = { "Alice", 30 };

5.2 Initializing after Declaration

Person person3;
person3.name = "Bob";
person3.age = 35;

6. Passing Structures as Function Arguments

Structures can be passed as function arguments, allowing you to manipulate the data contained within the structure. Consider the following example:

void displayPerson(const Person& p)

    std::cout << "Name: " << p.name << std::endl;
    std::cout << "Age: " << p.age << std::endl;

// Calling the function

7. Structures within Structures

In C++, structures can be nested within other structures, allowing for more complex data structures. Here’s an example:

struct Address {
    std::string street;
    std::string city;
    std::string state;

struct Contact {
    std::string name;
    Address address;

8. Differences between C++ Structures and C Structures

C++ structures offer several advantages over C structures, including:

  • C++ structures support member functions and can have constructors and destructors.
  • C++ structures can have inheritance, allowing for more complex object-oriented designs.
  • C++ structures can have access specifiers (public, private, protected), providing encapsulation and data hiding.

9. Is C++ a Structural Language?

C++ is a multi-paradigm programming language that supports procedural, object-oriented, and generic programming. While it does allow for structural programming, its capabilities extend beyond that. C++ combines the best of both worlds, offering both structured and object-oriented programming features.

10. Main Function in C++ Structure

In C++, the main() function serves as the entry point for the program. It is not specific to structures but rather the starting point for program execution. The main() function is where you typically define and use structures as needed.

11. Common Mistakes to Avoid

When working with structures in C++, it’s essential to avoid common mistakes such as:

  • Forgetting to initialize structure members.
  • Accessing structure members without creating an instance of the structure.
  • Not including the necessary header files when using standard library types inside structures.


In conclusion, C++ structures provide a powerful mechanism for organizing and manipulating data. They allow programmers to define custom data types, group related variables, and create complex data structures. By understanding the syntax, accessing members, and utilizing structures effectively, you can write efficient and maintainable C++ code.


Q: What are the structures of C++?

Structures in C++ are user-defined data types that allow the grouping of different variables under a single name.

Q: What is the difference between C++ Structures & C Structures?

C++ structures offer additional features such as member functions, constructors, destructors, and inheritance, which are not available in C structures.

Q: Is C++ a structural language?

While C++ supports structural programming, it is a multi-paradigm programming language that also offers object-oriented and generic programming capabilities.

Q: What is the main function in C++ structure?

The main() function in C++ serves as the entry point for the program and is not specific to structures.

Q: What is structure with example?

A structure in C++ is a user-defined data type that allows the grouping of different variables. For example, a “Person” structure may contain variables for name, age, and address.

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