Tests if a character string is a valid date.
$isdate(string)
| string | a character string or an expression that evaluates to a character string |
1-character binary string. Evaluates to 1 ($True) if string meets the validation test; otherwise, evaluates to 0 ($False).
This function tests if a particular character string is a valid date.
$isdate("19980606")
Evaluates to $True.
$isdate("19980229")
Evaluates to $False.
$isdate($date)
Evaluates to $True.
$isdate($date+30)
Evaluates to $True.