The return statement in C++ is used to exit a function and to send a value back to the function’s caller which is optional depending on requirement. It plays a very important role in controlling the flow of a program and making sure that functions will provide results to other parts of the code.
Syntax
Below is the syntax of using return statement in C++ −
return[expression];
Where, “expression” is optional, specifically used for function. If provided, it specifies the value to be returned to the caller.
Example of return Statement
The following is an example of return statement −
#include <iostream>usingnamespace std;intsum(int a,int b){// Here, returning sum of a and breturn a + b;}intmain(){// Calling the functionint ans =sum(5,2);
cout <<"The sum of two integers 5 and 2 is: "<< ans << endl;// Returning from the main (),// 0 represents execution done without any errorreturn0;}
Output
The sum of two integers 5 and 2 is: 7
Key Aspects of return Statement
1. Function Termination
When a return statement is executed, the function exits immediately, and optionally sends value back to the caller.
2. Returning Types
Return by Value
In this the specified value in return statement is sent back to the caller. This is essential for functions which perform calculations or need to provide results.
intAdd(int a,int b){return a + b;// Returns the sum of a and b}
No Return Value (void)
The functions which are declared with void, the return statement can be used without an expression to exit the function early.
voidGetMessage(){
cout <<"Hello, TutorialsPoint Learner!";return;// Exits the function}
3. Multiple return Statements
A function may consist of multiple return statements, which we generally get to see within conditional statements.
intmax(int a,int b){if(a > b)return a;elsereturn b;}
4. Returning Objects
Functions can return objects, which can be useful for returning multiple values encapsulated in a class or struct.
structpoint{int x, y;};
point getOrigin(){return{0,0};}
5. Early Exit
The return statement can be used to exit a function early, which is useful for error handling or special conditions.
intdivideInteger(int a,int b){if(b ==0){
cer <<"Error: Division by zero!"<< endl;return-1;// Shows an error}return a / b;}
Return Types and Value Handling in C++
In C++, the return type of a function determines what kind of value (if any) a function will return to the caller. Proper handling of return types and values is important for making sure that functions behave as expected and integrate smoothly with other parts of the program.
1. Primitive Data Types
Primitive data types are the basic built-in types provided by C++. Common examples are like int, float, double, char etc.
Example
#include <iostream>usingnamespace std;// created a function which returns an integerintgetSquare(int num){return num * num;}intmain(){int value =5;int result =getSquare(value);// Calling the function and storing its result
cout <<"The square of "<< value <<" is "<< result << endl;return0;}
Output
The square of 5 is 25
2. User-Defined Types
User-defined types include structs and classes. These types allow you to define complex data structures and customize them as per your specific requirements.
Example with Struct
#include <iostream>usingnamespace std;structPoint{int x;int y;};
Point createPoint(int x,int y){
Point p;
p.x = x;
p.y = y;return p;// will returns a Point object}intmain(){
Point p =createPoint(10,20);
cout <<"Point coordinates: ("<< p.x <<", "<< p.y <<")"<< endl;return0;}
Output
Point coordinates: (10, 20)
Example with Classes
#include <iostream>usingnamespace std;classrectangle{public:rectangle(int w,int h):width(w),height(h){}intgetArea()const{return width * height;}private:int width;int height;};
rectangle createRectangle(int width,int height){returnrectangle(width, height);// Returns a Rectangle object}intmain(){
rectangle rect =createRectangle(10,5);
cout <<"Area of given Rectangle is: "<< rect.getArea()<< endl;return0;}
Output
Area of given Rectangle is: 50
3. References and Pointers
References and pointers are used to refer to variables or objects without making any copies. Which can be useful for efficiency and and easy to modify the original data when needed.
Returning by Reference
#include <iostream>usingnamespace std;int globalValue =100;int&getGlobalValue(){return globalValue;// Returns a reference to the global variable}intmain(){int& ref =getGlobalValue();
ref =200;// Modifies the global variable
cout <<"Global Value: "<< globalValue << endl;return0;}
Output
Global Value: 200
Returning by Pointer
#include <iostream>usingnamespace std;int*createArray(int size){int* array =newint[size];// Allocating memory dynamicallyfor(int i =0; i < size;++i){
array[i]= i *10;}return array;// Returning a pointer to the allocated array}intmain(){int* myArray =createArray(5);for(int i =0; i <5;++i){
cout << myArray[i]<<" ";}delete[] myArray;// Free dynamically allocated memoryreturn0;}
Output
0 10 20 30 40
