is_nan
(PHP 4 >= 4.2.0, PHP 5)
is_nan — Finds whether a value is not a number
說明
bool is_nan
( float $val
)
Checks whether val is 'not a number', like the result of acos(1.01).
參數
- val
-
The value to check
Return值
Returns TRUE if val is 'not a number', else FALSE.