Introduction

In this post, we will discuss conditional execution using the if statement in C++ programs. C++ if statement in its simplest form and has the following syntax as below:

if(expression){
     // statements to be executed when the expression is true

}

Flowchart

If the expression is true the action is executed, otherwise the action is not executed. Basic flowchart of the if statement is shown in the picture.

Sample Code

/*************************
* C++ if statement demo
*************************/

#include <iostream>
using namespace std;

int main()
{
    int n;
    cout << "Please enter a number : " ;
    cin >> n;
    if(n > 0)
        cout << "Number is positive." << endl;
    return 0;
}

Sample run:

Please enter a number : 5
Number is positive.

Process returned 0 (0x0) execution time : 3.236 s
Press any key to continue.

*******************

Please enter a number : -5

Process returned 0 (0x0) execution time : 6.017 s
Press any key to continue.

*******************

 

 

if-else statement

In situations where different actions are to be executed based on the expression.

if(expression){
      action1

}
else {
      action2

}

 

 

/*************************
* C++ if statement demo
*************************/

#include <iostream>
using namespace std;

int main()
{
    int n;
    cout << "Please enter a number : " ;
    cin >> n;
    // if-else statement
    if(n > 0)
        cout << "Number is positive." << endl;
    else
        cout << "Number is negative." << endl;

    return 0;
}

Sample run

Please enter a number : 5
Number is positive.

Process returned 0 (0x0) execution time : 10.715 s
Press any key to continue.

**********************

Please enter a number : 5
Number is positive.

Process returned 0 (0x0) execution time : 10.715 s
Press any key to continue.

**********************

 

—

C++ Tutorials

C++ Tutorials on this website:

https://www.testingdocs.com/c-coding-tutorials/

For more information on the current ISO C++ standard

https://isocpp.org/std/the-standard