elif

Elif is a keyword in Python used to introduce additional conditional branches within a single if statement. It stands for "else if" and serves to test successive conditions without nesting.

Syntax and semantics: The structure begins with if, followed by one or more elif clauses and an optional else clause. Each clause consists of a condition and a block of statements. Python evaluates the conditions from top to bottom and executes the block of the first condition that evaluates to True; once a match is found, the rest of the chain is skipped. If none match and an else clause is present, its block runs. You may use any number of elif clauses; else is optional.

Best practices: Use elif when you have several mutually exclusive conditions. A long chain can reduce readability; in some cases a mapping or the match statement (introduced in Python 3.10) may offer a clearer alternative for complex patterns.

Comparison: Unlike languages that use else if as two tokens, Python uses a single elif keyword. It must appear after an if and before any else.

Example:

x = 7

if x < 0:

print("negative")

elif x == 0:

print("zero")

elif x > 0:

print("positive")

else:

print("unknown")

Elif remains a core part of conditional logic in Python, providing a concise means to handle multiple, exclusive cases within a single conditional chain.