The is_nan() function checks whether a value is 'not a number'.
This function returns true (1) if the specified value is 'not a number', otherwise it returns false/nothing.
bool is_nan ( mixed $val )
Checks whether val is 'not a number', like the result of acos(1.01).
Parameter | Description |
---|---|
val | The value to check |
Returns TRUE if val is 'not a number', else FALSE.