return Statement in C++
In C++, the return statement returns the flow of the execution to the function from where it is called. This statement does not mandatorily need any conditional statements. As soon as the statement is executed, the flow of the program stops immediately and returns the control from where it was called. The return statement may or may not return anything for a void function, but for a non-void function, a return value must be returned.
Let’s take a look at an example:
#include <iostream>
using namespace std;
int add(int a, int b) {
// Return the sum and terminate the function
return a + b;
}
int main() {
// Call the function and store the result
int res = add(5, 7);
cout << res;
return 0;
}
using namespace std;int add(int a, int b) { // Return the sum and terminate the function return a + b; }int main() { // Call the function and store the result int res = add(5, 7); cout << res; return 0;}Output
12
Explanation: In this example, in add() function, the return a + b returns the sum to the calling function and terminate the execution of the function. In the main function, return 0 indicates that the program executed successfully.
Syntax:
return expression[];
There are various ways to use return statements. A few are mentioned below:
1. Methods not returning a value
In C++ one cannot skip the return statement when the methods are of the return type. The return statement can be skipped only for void types.
Not using a return statement in void return type function
When a function does not return anything, the void return type is used. So if there is a void return type in the function definition, then there will be no return statement inside that function (generally).
Example:
// C++ code to show not using return
// statement in void return type function
#include <iostream>
using namespace std;
// void method
void Print()
{
cout << "Welcome to GeeksforGeeks";
}
// Driver method
int main()
{
// Calling print
Print();
return 0;
}
// C++ code to show not using return// statement in void return type functionusing namespace std;// void methodvoid Print(){ cout << "Welcome to GeeksforGeeks";}// Driver methodint main(){ // Calling print Print(); return 0;}Output
Welcome to GeeksforGeeks
Using the return statement in void return type function
Now the question arises, what if there is a return statement inside a void return type function? Since we know that, if there is a void return type in the function definition, then there will be no return statement inside that function. But if there is a return statement inside it, then also there will be no problem if the syntax of it will be:
This syntax is used in function just as a jump statement in order to break the flow of the function and jump out of it. One can think of it as an alternative to "break statement" to use in functions.
Example:
// C++ code to show using return
// statement in void return type function
#include <iostream>
using namespace std;
// void method
void Print()
{
cout << "Welcome to GeekforGeeks";
// void method using the return statement
return;
}
// Driver method
int main()
{
// Calling print
Print();
return 0;
}
// C++ code to show using return// statement in void return type functionusing namespace std;// void methodvoid Print(){ cout << "Welcome to GeekforGeeks"; // void method using the return statement return;}// Driver methodint main(){ // Calling print Print(); return 0;}Output
Welcome to GeekforGeeks
But if the return statement tries to return a value in a void return type function, that will lead to errors.
Incorrect Syntax:
void func() {
return value;
}
Example:
// C++ code to show using return statement
// with a value in void return type function
#include <iostream>
using namespace std;
// void method
void Print()
{
cout << "Welcome to GeeksforGeeks";
// void method using the return
// statement to return a value
return 10;
}
// Driver method
int main()
{
// Calling print
Print();
return 0;
}
// C++ code to show using return statement// with a value in void return type functionusing namespace std;// void methodvoid Print(){ cout << "Welcome to GeeksforGeeks"; // void method using the return // statement to return a value return 10;}// Driver methodint main(){ // Calling print Print(); return 0;}Output:
warning: 'return' with a value, in function returning void2. Methods returning a value:
For methods that define a return type, the return statement must be immediately followed by the return value of that specified return type.
Syntax:
return-type func() {
return value;
}
Example:
// C++ code to illustrate Methods returning
// a value using return statement
#include <iostream>
using namespace std;
// non-void return type
// function to calculate sum
int SUM(int a, int b)
{
int s1 = a + b;
// method using the return
// statement to return a value
return s1;
}
// Driver method
int main()
{
int num1 = 10;
int num2 = 10;
int sum_of = SUM(num1, num2);
cout << "The sum is " << sum_of;
return 0;
}
// C++ code to illustrate Methods returning// a value using return statementusing namespace std;// non-void return type// function to calculate sumint SUM(int a, int b){ int s1 = a + b; // method using the return // statement to return a value return s1;}// Driver methodint main(){ int num1 = 10; int num2 = 10; int sum_of = SUM(num1, num2); cout << "The sum is " << sum_of; return 0;}Output
The sum is 20
Note: We can only return a single value from a function using return statement. To return multiple values, we can use pointers, structures, classes, etc. To know more, click here.
