elseif

In computer programming, else if is a conditional control-flow construct that introduces an additional test when previous conditions in an if-else chain have failed. It enables a program to select among several mutually exclusive execution paths.

In languages derived from C, the form is written as else if with a space, though some languages provide a single keyword such as elseif or elsif.

Semantics: Conditions are evaluated sequentially from the top. When a condition evaluates to true, its block executes and the remainder of the ladder is skipped; if none match, an optional final else handles the default path.

Usage considerations: Keep conditions simple and non-overlapping, order branches by likelihood or specificity, and avoid duplicating logic. For long chains, consider refactoring into a dispatch table, a switch statement, or guard clauses.

Language variants: Ruby uses elsif; Python uses elif; PHP supports elseif and also else if for compatibility. These variants reflect differing syntax but preserve the same core idea of testing additional conditions only after earlier ones have failed.

See also: if statement; switch statement.