If / Else

Cairo supports the condition statements if and if ... else. else if statements are currently not supported.

Conditions can be combined with the and operator.

In addition to the regular conditional statement one can also use the "Multiplication Trick" to create an inline-if condition statement (conditional ternary operator).

Example

# Importing booleans from Cairos standard library.
from starkware.cairo.common.bool import TRUE, FALSE

func main():
    alloc_locals

    local result

    # `if` statement.
    if 1 == 0:
        result = FALSE
    end

    assert result = TRUE

    # `if` statement with `and`.
    if 1 == 0 and 0 == 1:
        result = FALSE
    end

    assert result = TRUE

    # `if` - `else` statement.
    if 1 == 1:
        result = TRUE
    else:
        result = FALSE
    end

    assert result = TRUE

    # The condition we want to check
    let condition = 1
    # The "Multiplication Trick".
    # `result` will be `0` (false) if `condition` is either `1` or `2`.
    # Note: This trick helps to avoid issues related to Revoked References.
    let result = (condition - 1) * (condition - 2)

    assert result = 0

    return ()
end