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Usage

Functions​

clamp()​

clamp(mixed $value, mixed $min, mixed $max): mixed

Returns $value clamped to the range [$min, $max]. This is the recommended function — it uses direct comparisons and is the faster of the two implementations.

clampMinMax()​

clampMinMax(mixed $value, mixed $min, mixed $max): mixed

Equivalent to clamp() in every way, including accepted types and error behaviour. It uses the max($min, min($max, $value)) approach internally and runs about 2× slower. See Performance for details.

Accepted types​

Arguments may be integers, floats, strings, or any objects that support comparison (e.g. DateTimeInterface). Mixed numeric types are allowed.

clamp(2, min: 1, max: 3);   // 2
clamp(0, min: 1, max: 3);   // 1
clamp(6, min: 1, max: 3);   // 3

clamp(2, 1.3, 3.4);         // 2
clamp(2.5, 1, 3);           // 2.5
clamp(0, 1.3, 3.4);         // 1.3

clamp(M_PI, -INF, INF);     // 3.141592653589793
clamp(NAN, 4, 6);           // NAN  — NAN is returned unchanged

clamp("a", "c", "g");       // "c"
clamp("d", "c", "g");       // "d"

clamp(
    new DateTimeImmutable('2025-08-01'),
    new DateTimeImmutable('2025-08-15'),
    new DateTimeImmutable('2025-09-15')
)->format('Y-m-d');         // "2025-08-15"

Errors​

A ValueError is thrown when the bounds are invalid. Both functions behave identically.

Invalid range — $min must be less than or equal to $max:

clamp(4, 8, 6);
// ValueError: clamp(): Argument #2 ($min) must be smaller than or equal to argument #3 ($max)

NAN bounds — NAN is not allowed as a bound (only as the value):

clamp(4, NAN, 6);
// ValueError: clamp(): Argument #2 ($min) cannot be NAN

clamp(4, 6, NAN);
// ValueError: clamp(): Argument #3 ($max) cannot be NAN