all Python 3Arithmetic & operatorsterm

Chained comparisons

comparison

Python lets you write several comparisons in a row in one expression. 1 < x < 10 is equivalent to (1 < x) and (x < 10) and is evaluated left to right.

Syntax

a < b < c  a == b == c  a <= b >= c

The middle operand is evaluated exactly once, and the chain short-circuits: if the first comparison is false, the second is never run. Hence the classic trap — x != y != z does not mean all three differ, it only checks neighbouring pairs, so x and z may well be equal.

Examples

x = 5
print(1 < x < 10)      # → True
print(1 < x < 4)       # → False
print(1 == 1 == 1)     # → True
print(1 == 1 == 2)     # → False
print(0 <= x <= 100)   # → True
print(10 > x > 0)      # → True

See also

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