if statement

 

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Conditionally executes code.

Used where code needs to be executed only if some condition is present.

Syntax

if ( expression ) statement_true
if ( expression ) statement_true else statement_false

Explanation

expression shall be an expression, convertible to bool.

If it evaluates to true, control is passed to statement_true, statement_false (if present) is not executed.

Otherwise, control is passed to statement_false, statement_true is not executed.

Keywords

if, else

Example

The following example demonstrates several usage cases of the if statement

#include <iostream>
 
int main()
{
    int i = 2;
    if (i > 2) {
        std::cout << "first is true" << '\n';
    } else {
        std::cout << "first is false" << '\n';
    }
 
    i = 3;
    if (i == 3) std::cout << "i == 3" << '\n';
 
    if (i != 3) std::cout << "i != 3" << '\n';
    else        std::cout << "i != 3 is false" << '\n';
}

Output:

first is false
i == 3
i != 3 is false