C++ if Statement

In this page:

Basic if Statement
Comparison inside if Condition
Logical AND in if Conditions
Logical OR in if Conditions
Nested if Statements

Basic if Statement

An if statement evaluates a condition and executes its associated block only when that condition is true; when it's false, the block is skipped entirely and execution continues right after it. This is the most fundamental building block for making a program's behavior depend on data rather than always doing the same thing.

Example: Basic if Statement

cpp

#include <iostream>

int main() {
	int age = 20;
	if (age >= 18) {
		std::cout << "Adult" << std::endl;
	}
	return 0;
}

Comparison inside if Condition

Comparison operators like == inside an if condition let you branch based on whether two values match, such as if (userChoice == y). Be careful not to accidentally type a single = here, since that would assign instead of compare and would almost always evaluate to true regardless of the actual values.

Example: Comparison inside if Condition

cpp

#include <iostream>

int main() {
	char userChoice = 'y';
	if (userChoice == 'y') {
		std::cout << "Confirmed" << std::endl;
	}
	return 0;
}

Logical AND in if Conditions

Combining two conditions with && inside an if requires both to be true before the block runs, such as if (age >= 18 && hasLicense), which only grants access when every requirement is satisfied simultaneously. This is how you express 'all of these things must hold' in code.

Example: Logical AND in if Conditions

cpp

#include <iostream>

int main() {
	int age = 20;
	bool hasLicense = true;
	if (age >= 18 && hasLicense) {
		std::cout << "Can drive" << std::endl;
	}
	return 0;
}

Logical OR in if Conditions

Using || instead lets the block run if at least one condition is true, such as if (isWeekend || isHoliday), useful whenever any single qualifying condition should be enough to proceed. Mixing && and || in one condition often needs parentheses to make the intended grouping unambiguous.

Example: Logical OR in if Conditions

cpp

#include <iostream>

int main() {
	bool isWeekend = false;
	bool isHoliday = true;
	if (isWeekend || isHoliday) {
		std::cout << "No work today" << std::endl;
	}
	return 0;
}

Nested if Statements

Placing one if inside another lets you check a second condition only once the first has already passed, such as verifying a user is logged in before separately checking whether they have admin rights. This mirrors real decision-making, where some questions only make sense to ask after an earlier one has already been answered.

Example: Nested if Statements

cpp

#include <iostream>

int main() {
	bool isLoggedIn = true;
	bool isAdmin = true;
	if (isLoggedIn) {
		if (isAdmin) {
			std::cout << "Welcome, admin" << std::endl;
		}
	}
	return 0;
}

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