Efficient Multi-Choice Logic

If you are comparing a single variable against many fixed values (like a menu with options 1, 2, 3, 4), a switch statement is much cleaner and often faster than a long else if ladder.

Syntax

switch (variable) {
    case 1:
        // code for option 1
        break;
    case 2:
        // code for option 2
        break;
    default:
        // code if no case matches
}

The Golden Rules of Switch

1. Integers and Characters ONLY: You can only switch on int, char, or enum. You cannot use float, double, or string.
2. Constants ONLY: You can only use fixed values in the case. You cannot say case x: (if x is a variable) or case > 10:.
3. The break is MANDATORY: If you forget the break, C will "fall through" and execute all the code for the following cases too! This is a very common bug.
4. The default case: This is your safety net. It runs if the variable doesn't match any of your cases.

When to use Switch vs If-Else?

• Use Switch for a large number of discrete, fixed choices. It's faster because the compiler can use a "Jump Table" to find the right case instantly.
• Use If-Else for ranges (score > 80), complex logic using && or ||, or when comparing floating-point numbers.

Clever Use: Intentional Fall-Through

Sometimes you want multiple cases to do the same thing.

switch (grade) {
    case 'A':
    case 'B':
    case 'C':
        printf("You passed!\n");
        break;
    case 'F':
        printf("You failed.\n");
        break;
}

Logical fall-through is one of the most common sources of errors in C. Always double-check that every case ends with a break unless you are explicitly trying to group cases together.