7.4: Structures in C++ (cont'd)

1. Member functions inside structure: Structures in C cannot have member functions inside structure but Structures in C++ can have member functions along with data members.
2. Direct Initialization: We cannot directly initialize structure data members in C but we can do it in C++.

// CPP program to initialize data member in c++ 
#include <iostream> 
using namespace std; 

struct Record {
   int x = 7; 
}; 

// Driver Program 
int main() 
{ 
   Record s; 
   cout << s.x << endl; 
   return 0; 
} 
// Output 
// 7 

 

3. Using struct keyword: In C, we need to use struct to declare a struct variable. In C++, struct is not necessary. For example, let there be a structure for Record. In C, we must use “struct Record” for Record variables. In C++, we need not use struct and using ‘Record‘ only would work.
4. Static Members: C structures cannot have static members but is allowed in C++.

// C++ program with structure static member

struct Record { 
   static int x; 
};

// Driver program 
int main() 
{ 
    return 0; 
}

5. Constructor creation in structure: Structures in C cannot have constructor inside structure but Structures in C++ can have Constructor creation.

// C program to illustrate empty structure 
#include <stdio.h>

// empty structure 
struct Record { 


};

6. sizeof operator: This operator will generate 0 for an empty structure in C whereas 1 for an empty structure in C++.

// Driver program 
int main() 
{ 
   struct Record s; 
   printf("%d\n", sizeof(s)); 
   return 0; 
}

Output in C++:

1

7. Data Hiding: C structures do not allow concept of Data hiding but is permitted in C++ as C++ is an object oriented language whereas C is not.
8. Access Modifiers: C structures do not have access modifiers as these modifiers are not supported by the language. C++ structures can have this concept as it is inbuilt in the language.

 

Adapted from: "Difference between C structures and C++ structures" by Gyanendra Singh Panwar is licensed under CC BY-SA 4.0