Derived Data Types in C++

Data types are means to identify the type of data and associated operations of handling it. There are three types of data types:

In this article, the Derived Data Type is explained:

Derived Data Types

The data-types that are derived from the primitive or built-in datatypes are referred to as Derived Data Types. These can be of four types namely:

Let’s briefly understand each of the following derived datatypes:

Function: A function is a block of code or program-segment that is defined to perform a specific well-defined task. A function is generally defined to save the user from writing the same lines of code again and again for the same input. All the lines of code are put together inside a single function and this can be called anywhere required. main() is a default function that is defined in every program of C++.

Syntax:

FunctionType FunctionName(parameters)

Example:

// C++ program to demonstrate 
// Function Derived Type 
  
#include <iostream> 
using namespace std; 
  
// max here is a function derived type 
int max(int x, int y) 
{ 
    if (x > y) 
        return x; 
    else
        return y; 
} 
  
// main is the default function derived type 
int main() 
{ 
    int a = 10, b = 20; 
  
    // Calling above function to 
    // find max of 'a' and 'b' 
    int m = max(a, b); 
  
    cout << "m is " << m; 
    return 0; 
} 

Output:

m is 20

Array: An array is a collection of items stored at continuous memory locations. The idea of array is to represent many instances in one variable.

Syntax:

DataType ArrayName[size_of_array];

Example:

// C++ program to demonstrate 
// Array Derived Type 
  
#include <iostream> 
using namespace std; 
int main() 
{ 
  
    // Array Derived Type 
    int arr[5]; 
    arr[0] = 5; 
    arr[2] = -10; 
  
    // this is same as arr[1] = 2 
    arr[3 / 2] = 2; 
  
    arr[3] = arr[0]; 
  
    cout<<arr[0]<<" "<<arr[1]<<" "<<arr[2]<<" "<<arr[3]; 
  
    return 0; 
} 

Output:

5 2 -10 5

Pointers: Pointers are symbolic representation of addresses. They enable programs to simulate call-by-reference as well as to create and manipulate dynamic data structures. It’s general declaration in C/C++ has the format:

Syntax:

datatype *var_name;

Example:

int *ptr;   

ptr points to an address
which holds int data

Example:

// C++ program to illustrate 
// Pointers Derived Type 
  
#include <bits/stdc++.h> 
using namespace std; 
  
void geeks() 
{ 
    int var = 20; 
  
    // Pointers Derived Type 
    // declare pointer variable 
    int* ptr; 
  
    // note that data type of ptr 
    // and var must be same 
    ptr = &var; 
  
    // assign the address of a variable 
    // to a pointer 
    cout << "Value at ptr = "
         << ptr << "\n"; 
    cout << "Value at var = "
         << var << "\n"; 
    cout << "Value at *ptr = "
         << *ptr << "\n"; 
} 
  
// Driver program 
int main() 
{ 
    geeks(); 
} 

Output:

Value at ptr = 0x7ffc10d7fd5c
Value at var = 20
Value at *ptr = 20

Reference: When a variable is declared as reference, it becomes an alternative name for an existing variable. A variable can be declared as reference by putting ‘&’ in the declaration.

Example:

// C++ program to illustrate 
// Reference Derived Type 
  
#include <iostream> 
using namespace std; 
  
int main() 
{ 
    int x = 10; 
  
    // Reference Derived Type 
    // ref is a reference to x. 
    int& ref = x; 
  
    // Value of x is now changed to 20 
    ref = 20; 
    cout << "x = " << x << endl; 
  
    // Value of x is now changed to 30 
    x = 30; 
    cout << "ref = " << ref << endl; 
  
    return 0; 
} 

Output:

x = 20
ref = 30

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Derived Data Types

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