(PHP 4 >= 4.2.0, PHP 5, PHP 7)
Finds whether a value is not a number
bool is_nan ( float $val )
Checks whether val is 'not a number', like the result of acos(1.01).
Parameters:
val
The value to check
Returns:
Returns TRUE if val is 'not a number', else FALSE.
Examples:
is_nan() example
<?php // Invalid calculation, will return a // NaN value $nan = acos(8); var_dump($nan, is_nan($nan)); ?>
The above example will output:
float(NAN) bool(true)
See also:
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