Returning values from a function in C++

By: Abinaya Emailed: 1700 times Printed: 2204 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

Functions return a value or return void. Void is a signal to the compiler that no value will be returned.

To return a value from a function, write the keyword return followed by the value you want to return. The value might itself be an expression that returns a value. For example:

return 5;
return (x > 5);
return (MyFunction());

These are all legal return statements, assuming that the function MyFunction() itself returns a value. The value in the second statement, return (x > 5), will be zero if x is not greater than 5, or it will be 1. What is returned is the value of the expression, 0 (false) or 1 (true), not the value of x.

When the return keyword is encountered, the expression following return is returned as the value of the function. Program execution returns immediately to the calling function, and any statements following the return are not executed.

It is legal to have more than one return statement in a single function. Program below illustrates this idea.

A demonstration of multiple return statements.

1:     // Demonstrates multiple return
2:     // statements
4:     #include <iostream.h>
6:     int Doubler(int AmountToDouble);
8:     int main()
9:     {
11:         int result = 0;
12:         int input;
14:         cout << "Enter a number between 0 and 10,000 to double: ";
15:         cin >> input;
17:         cout << "\nBefore doubler is called... ";
18:         cout << "\ninput: " << input << " doubled: " << result << "\n";
20:         result = Doubler(input);
22:         cout << "\nBack from Doubler...\n";
23:         cout << "\ninput: " << input << "   doubled: " << result << "\n";
26:         return 0;
27:    }
29:    int Doubler(int original)
30:    {
31:         if (original <= 10000)
32:              return original * 2;
33:         else
34:              return -1;
35:         cout << "You can't get here!\n";
36: }
Output: Enter a number between 0 and 10,000 to double: 9000

Before doubler is called...
input: 9000 doubled: 0

Back from doubler...

input: 9000   doubled: 18000

Enter a number between 0 and 10,000 to double: 11000

Before doubler is called...
input: 11000 doubled: 0

Back from doubler...
input: 11000  doubled: -1

Analysis: A number is requested on lines 14 and 15, and printed on line 18, along with the local variable result. The function Doubler() is called on line 20, and the input value is passed as a parameter. The result will be assigned to the local variable result, and the values will be reprinted on lines 22 and 23.
On line 31, in the function Doubler(), the parameter is tested to see whether it is greater than 10,000. If it is not, the function returns twice the original number. If it is greater than 10,000, the function returns -1 as an error value.

The statement on line 35 is never reached, because whether or not the value is greater than 10,000, the function returns before it gets to line 35, on either line 32 or line 34. A good compiler will warn that this statement cannot be executed, and a good programmer will take it out!

C++ Home | All C++ Tutorials | Latest C++ Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.

Bookmark and Share


Be the first one to add a comment

Your name (required):

Your email(required, will not be shown to the public):

Your sites URL (optional):

Your comments:

More Tutorials by Abinaya
How to compile a Java program - javac
The clone() Method in Java
Data Types in Java
JSP Example to connect to MS SQL database and retrieve records
faces-config.xml to DirectTraffic in the JSF Application
Enabling Expression Language Evaluation in JSP
Using malloc() Function in C
ActionErrors and ActionError in Struts
Open, Creat, Close, Unlink system calls sample program in C
Structures and Functions in C
Introduction to JSP expression language
Multi-dimensional Arrays in C (Explained using date conversion program)
A C program similar to grep command in UNIX
Type Conversions in C (String to Integer, isdigit() etc)
Basics of C

More Tutorials in C++
Two-Dimensional Array Manipulation in C++
Calculate average using Two-Dimensional Array in C++
Compute the square root of the sum of the squares of an array in C++
Matrix using nested for loops in C++
Sorting an array of Strings in C++
Calculating total based on the given quantity and price in C++
Compiling and Linking Multiple Source Files in C++
Enumerations in C++
Program to add two numbers in C++
Comments in C++
while loop in C++
for loop in C++
Programming errors a compiler will detect in C++
if in C++
Using the Built-in Arithmetic Types in C++

More Latest News
Most Viewed Articles (in C++ )
Using cout in C++
Demonstration of Prefix and Postfix operators in C++
Use of Conditional (Ternary) Operator in C++
Demonstrating global and local variables in C++
Passing parameters to a function by value in C++
Returning values from a function in C++
The Birth, history and need for C++
Tutorial on Classes and Members in C++
Constructors and Destructors in C++
const Member Functions in C++
Where to Put Class Declarations and Method Definitions in C++
Tutorial on Inline Implementation in C++
Classes with Other Classes as Member Data in C++
Looping with the keyword goto in C++
while Loops in C++
Most Emailed Articles (in C++)
while (1) Loops in C++
How to handle Exceptions in C++
Character String Literals in C++
Calculating total based on the given quantity and price in C++
A Brief History of C++
Difference between Procedural, Structured, and Object-Oriented Programming
C++ and Object-Oriented Programming
Getting Started with C++
Using cout in C++
Using Comments in a C++ Program
Using functions in C++
How to use Enumerated constants in C++
Demonstration of Prefix and Postfix operators in C++
The if Statement in C++
Advanced if Statements in C++