Câu lệnh có điều kiện (if-else)

Conditional statements allow executing different blocks of code based on whether certain conditions are met.

In C++, the fundamental construct is if, optionally followed by else if and else.

The if-else Structure

The basic syntax requires enclosing the condition in parentheses () and the block of code in curly braces {}:

int temperature = 25;

if (temperature > 30) {
    std::cout << "It's very hot!" << std::endl;
} else if (temperature >= 20) {
    std::cout << "The temperature is pleasant." << std::endl;
} else {
    std::cout << "It's cold." << std::endl;
}

Valid Conditional Expressions

Any expression that returns a value convertible to boolean can be used as a condition:

• In C++, the value 0 or the pointer nullptr are considered false.
• Any value other than 0 (positive or negative) is considered true.

int activeUsers = 5;
if (activeUsers) {
    // This block runs because activeUsers is not 0 (true)
}

Try it yourself