Logical Conditions with if

Logical Conditions with if

Real conditions are rarely a single comparison. Combine them with the logical operators &&, ||, and !.

AND in a condition

int age = 25;
int height = 175;
if (age > 18 && height > 170) {
    printf("Can ride the coaster!");
}

Both must be true.

OR in a condition

int day = 0;   // Sunday
if (day == 6 || day == 0) {
    printf("Weekend!");
}

At least one must be true.

NOT in a condition

int isLoggedIn = 0;
if (!isLoggedIn) {
    printf("Please log in.");
}

Short-circuiting

C evaluates left to right and stops early. In a && b, if a is false, b is never evaluated.

TL;DR

• && both sides must be true.
• || at least one side must be true.
• ! flips a condition.
• C short-circuits logical conditions to save work.