Check whether a value is 'not-a-number':
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.
Parameter | Description |
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value | Required. Specifies the value to check |
Return Value: | TRUE if value is 'not a number', FALSE otherwise |
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Return Type: | Boolean |
PHP Version: | 4.2+ |