Function Returning Pointer in C++

 Function Returning Pointer

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Introduction

A function can return a pointer — i.e., the address of a variable instead of its actual value.

Returning a pointer is useful when:

• Return large data efficiently (without copying)
• Modify variables outside the function
• Return arrays or dynamically allocated memory

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Syntax

datatype* function_name(parameters);

 

Example:

int* getNumber();

 

Function getNumber() will return a pointer to int (i.e., an int address).

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Example 1 – Returning Address of a Variable

#include <iostream>

using namespace std;

 

int* findMax(int* a, int* b) {

    if (*a > *b)

        return a;   // return address of a

    else

        return b;   // return address of b

}

 

int main() {

    int x = 10, y = 20;

    int* result = findMax(&x, &y);

    cout << "Maximum = " << *result;

    return 0;

}

 

Output:

Maximum = 20

Example 2 – Returning Pointer from Function (with Local Variable )

Note:- Never return a pointer to a local variable — it becomes invalid when the function ends.

 

Wrong Example:

int* demo() {

    int x = 10;

    return &x;   //  x is local variable → memory destroyed after function ends

}

This leads to undefined behavior.

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Correct Way: Use static or new

(a) Using a static variable:

int* demo() {

    static int x = 10;

    return &x;   // valid, x persists even after function ends

}

(b) Using new (Dynamic Memory):

int* demo() {

    int* p = new int;

    *p = 10;

    return p;   // valid, memory remains until deleted manually

}

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Example 3 – Returning Pointer Using Dynamic Memory

#include <iostream>

using namespace std;

 

int* createArray(int n) {

    int* arr = new int[n];   // dynamically allocate memory

    for (int i = 0; i < n; i++)

        arr[i] = i + 1;

    return arr;   // return base address

}

 

int main() {

    int n = 5;

    int* p = createArray(n);

 

    cout << "Array elements: ";

    for (int i = 0; i < n; i++)

        cout << p[i] << " ";

 

    delete[] p;  // free memory

    return 0;

}

Output:

Array elements: 1 2 3 4 5

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Real-Life Uses

• Returning the array base address
• Returning a structure or object pointer
• Allocating memory using new
• Pointer-based linked list, tree, stack, etc.

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