Switch Statements

The switch statement lets you compare a single expression against multiple possible values. Depending on the matched value, it runs a different block of code.

It’s a less cluttered alternative to using long if/else if chains when you’re comparing one variable against several fixed values.

A basic switch statement

The basic syntax is

The switch keyword is followed by an expression in parentheses. This expression is evaluated and then matched against each value listed after the case keyword, in order. If a value is matched, all code up to the next break; statement is executed.

If no case matches, the default case is executed.

Example

Here’s an example that maps a number to the name of the day:

As day holds 3, the program matches case 3:, prints Wednesday, and then stops at break; on line 15. The other cases are skipped entirely.

Key rules

1. The expression must produce an integer or character value, like int, char, or enum (you’ll meet enums later). You cannot use switch on strings, floats, or doubles.
2. The case values must be constants.
3. The break; statement stops execution. Without it, code “falls through” to the next case.
4. The default case is optional, but it’s considered good practice since it catches unmatched values.

The break keyword, and why it exists

As mentioned above, if you omit break;, execution continues into the next case. This is called fall-through. Fall-through was designed to group cases, so it can be used intentionally, as in the following example:

Here, 'A' and 'B' share the same output because there’s no break between them. Likewise with 'C' and 'D'.

A pitfall: Forgetting the break is a common mistake. Some people make a habit of writing break as soon as they write the case line, then fill in the logic afterwards.

Using switch versus if/else if

Both let you branch on conditions, so how do you decide which to use?

Developers reach for switch when they’re comparing one variable against several known values, checking each for equality. They tend to default to if/else if when conditions involve ranges, multiple variables, or anything beyond a direct equality check, like length >= 10 or x > 0 && y > 0.