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Table of contents
1.
Introduction 
2.
What is the structure in C?
3.
What is the structure in C++?
4.
Differences between structures in C and C++
5.
Member functions
5.1.
C
5.2.
C++
6.
Static Members 
7.
Constructors Creation 
7.1.
C
8.
Direct Initialization 
8.1.
C
9.
Using “struct” keyword
9.1.
C
10.
“sizeof” Operator 
10.1.
C++
10.2.
C
11.
Access Modifiers 
12.
Pointers and References 
13.
Data Hiding 
14.
Similarities Between the C and C++ Structures
15.
Frequently Asked Questions 
15.1.
What is the difference between structure in C and structure in C++?
15.2.
What is the difference between data structure and C++?
15.3.
What is the difference between class in C++ and struct in C?
15.4.
How many types of structures are there in C++?
15.5.
What is structure in C++ with example?
16.
Conclusion
Last Updated: Jul 9, 2024
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Difference between Structure in C and C++

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Introduction 

In programming languages, C and C++ stand as stalwarts, each wielding their unique features and syntax. Among the fundamental building blocks they share is the concept of structures. However, delving deeper reveals subtle yet significant differences in how structures are handled in these languages.

Difference between Structure in C and C++

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What is the structure in C?

In C programming, a structure is a composite data type that allows you to group together variables of different data types under a single name. It enables you to create custom data types to represent entities with multiple attributes. Structures in C do not support member functions or inheritance and are primarily used for organizing related data.

Here's a simple example of a structure in C:

#include <stdio.h>

// Defining a structure
struct Person {
    char name[50];
    int age;
};

int main() {
    // Declaring structure variables
    struct Person person1, person2;

    // Assigning values to structure members
    strcpy(person1.name, "John");
    person1.age = 30;

    // Accessing structure members
    printf("Person 1: Name = %s, Age = %d\n", person1.name, person1.age);

    return 0;
}
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What is the structure in C++?

In C++, structures are similar to those in C but with additional features. C++ introduced the concept of classes, which are essentially enhanced versions of structures. However, C++ still supports traditional structures. In C++, structures can have member functions, constructors, destructors, and access specifiers (public, private, protected). Additionally, C++ structures can participate in inheritance, making them more versatile than their C counterparts.

Here's an example of a structure in C++:

#include <iostream>
#include <string>

// Defining a structure
struct Person {
    std::string name;
    int age;

    // Member function to display information
    void display() {
        std::cout << "Name: " << name << ", Age: " << age << std::endl;
    }
};

int main() {
    // Declaring structure variables
    Person person1, person2;

    // Assigning values to structure members
    person1.name = "John";
    person1.age = 30;

    // Accessing structure members
    person1.display();

    return 0;
}

Differences between structures in C and C++

The main differences between the structures of C and C++ are as follows. 

AspectStructures in CStructures in C++
Member FunctionsCannot contain member functions.Can contain member functions, allowing for encapsulation and behavior associated with the data.
ConstructorsDoes not support constructors.Supports constructors, allowing for initialization of structure members when an object is created.
DestructorsDoes not support destructors.Does not support destructors in structures (except in classes).
Access SpecifiersDoes not support access specifiers.Supports access specifiers (public, private, protected), providing control over member accessibility.
InheritanceCannot participate in inheritance.Can participate in inheritance, enabling the creation of derived structures/classes with shared attributes and behaviors.
EncapsulationLimited encapsulation capabilities.Offers better encapsulation through member functions and access specifiers, allowing for data hiding and controlled access.
Default Member VisibilityAll members have public visibility by default.Members have private visibility by default, encouraging encapsulation and information hiding.

You can also do a free certification of Basics of C++.

Let’s Discuss all the differences between C and C++ structures in detail. 

Member functions

As previously stated, C structures cannot have member functions, but C++ structures can have.

C Code:

  • C

C

// C Program to Implement Member
// functions inside structure
#include <stdio.h>
#include<stdlib.h>
struct example {
   int marks;
 
   // defining member functin to initialize the value of marks
   void initialize(int num) { marks = num; }

   // function used to display the marks
   void display() { printf("%d", marks); }
};

// Driver Program
int main()
{
   struct example c1;
   // calling function inside Struct to
   // initialize value to marks
   c1.initialize(9);

   // calling function inside struct to
   // display value of marks
   c1.display();
}

Output

C code will produce the error, as member functions not allowed in C. 

 

C++ Code:

  • C++

C++

// C++ Program to Implement Member
// functions inside structure
#include<bits/stdc++.h>
using namespace std;
struct example {
   int marks;
 
   // defining member functin to initialize the value of marks
   void initialize(int num) { marks = num; }

   // function used to display the marks
   void display() { cout << “Marks = ” << marks; }
};

// Driver Program
int main()
{
   struct example c1;
   // calling function inside Struct to
   // initialize value to marks
   c1.initialize(9);

   // calling function inside struct to
   // display value of marks
   c1.display();
}

Output

Marks = 9

You can try and compile with the help of online c++ compiler.

Static Members 

C cannot have static members while C++ can have static members in struct. 

struct example {
    static int temp;
};
// Driver Program
int main()
{return 0;}

 

Output:

 This code will produce errors in C but not in C++. 

Constructors Creation 

Construtor creation is allowed in C++ but not in C language 

  • C

C

struct example {
   int marks;
 
   // constructor to initialize
   example(int num) { marks = num; }
};

// Driver Program
int main()
{
   // initializing an object and
   // giving value using constructor 
   struct example c1(9);
   printf("%d", c1.marks);
}

C Output:

 error

 

C++ Output

9

Also Read - C++ Interview Questions

Direct Initialization 

We can directly initialize a structure in C++ but not in C language. 

  • C

C

struct example {
   int val = 100;
};

// Driver Program
int main()
{
   struct example c1;
   printf("%d", c1.val);
}

C Output

error

 

C++ Output

100

Using “struct” keyword

  • C

C

struct example {
   int val;
};

// Driver Program
int main()
{
   example c1;
   c1.val = 100;
   printf("%d", c1.val);
}

C Output

Error, because we have not used the struct keyword. 

 

C++ Ouput:

 100 

“sizeof” Operator 

In C, this operation returns 0 for an empty structure, but in C++, it returns 1.

C++ Code:

  • C++

C++

struct example {
};

// Driver Program
int main()
{
   example c1;
   cout << sizeof(c1) << endl;
}

Output

1 

 

C Code:

  • C

C

struct example {
};

// Driver Program
int main(){
   example c1;
   printf("%d", sizeof(c1));
}

Output

0

Access Modifiers 

Because the language does not permit access modifiers, C structures do not have them. Because this idea is incorporated into the language, it may be used in C++ structures.

Pointers and References 

Both pointers and references to structs are allowed in C++, whereas only pointers to structs are allowed in C. 

Data Hiding 

Data hiding is not allowed in C structures; however, it is allowed in C++ since it is an object-oriented language, but C is not.

Also see, Fibonacci Series in C++, Abstract Data Types in C++ 

Similarities Between the C and C++ Structures

While there are notable differences between structures in C and C++, there are also similarities that underscore their shared foundational principles:

  • Member Variables: Both C and C++ structures allow grouping together variables of different data types under a single name.
  • Data Organization: Structures in both languages serve the purpose of organizing related data into a single unit, enhancing code clarity and maintainability.
  • Syntax: The basic syntax for defining and accessing structure members is similar in both languages, making it easier for developers familiar with one language to understand the other.
  • Memory Allocation: Structures in both languages typically occupy contiguous memory locations, enabling efficient storage and retrieval of data.
  • Use Cases: Structures in both C and C++ are commonly used for representing entities with multiple attributes, such as employees, students, or complex data structures.

Frequently Asked Questions 

What is the difference between structure in C and structure in C++?

Structures in C are limited to grouping data variables, lacking member functions and access specifiers. In contrast, C++ structures support member functions, constructors, access specifiers, and can participate in inheritance, offering enhanced encapsulation and versatility.

What is the difference between data structure and C++?

Data structures refer to specialized formats for organizing, managing, and storing data efficiently, encompassing arrays, linked lists, trees, etc. C++ is a programming language that provides tools and features, including classes and templates, for implementing and manipulating data structures.

What is the difference between class in C++ and struct in C?

In C++, classes and structs share similar syntax and capabilities, but the default member visibility differs: class members default to private, while struct members default to public. Additionally, structs in C++ can contain member functions, constructors, and access specifiers like classes.

How many types of structures are there in C++?

In C++, there's only one type of structure, which is defined using the struct keyword. However, structures in C++ can be customized with member functions, constructors, and access specifiers to suit different programming needs.

What is structure in C++ with example?

In C++, a structure is a user-defined data type that allows bundling together variables of different types under a single name. For example:

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

   // Constructor
   Person(std::string n, int a) : name(n), age(a) {}

   // Member function
   void display() {
       std::cout << "Name: " << name << ", Age: " << age << std::endl;
   }
};

Conclusion

In this article, we discussed are main differences between structures in C and C++. Understanding the disparities between structures in C and C++ sheds light on the evolution of programming languages and the enhanced capabilities they offer. While C structures provide a basic mechanism for data organization, C++ structures enrich this concept with features like member functions, constructors, access specifiers, and inheritance.

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