IsDate - VBScript

IsDate

This function determines whether a string represents a valid date. It is commonly used to test user input or to check whether a value is in a date format.

Syntax

IsDate(expression)

Options/Flags

None

Examples

Simple usage:

If IsDate("2023-03-08") Then
    Debug.Print "The string is a valid date."
End If

Complex usage:

Dim dateString As String = InputBox("Enter a date:")

If IsDate(dateString) Then
    Select Case Len(dateString)
        Case 10
            ' Format: YYYY-MM-DD
        Case 8
            ' Format: YYYYMMDD
        Case 6
            ' Format: YYMMDD
        Case Else
            ' Invalid date format
    End Select
Else
    Debug.Print "Invalid date format."
End If

Common Issues

Type mismatch error: Ensure that the expression provided to IsDate is a string.
Invalid date format: The string must be in a recognized date format (e.g., “YYYY-MM-DD”, “MM/DD/YYYY”).

Integration

IsDate can be combined with other functions to perform more complex date operations. For example:

Dim today As Date = Date
If IsDate(InputBox("Enter a date:")) Then
    Dim dateToCompare As Variant = CDate(InputBox("Enter a date:"))
    If dateToCompare > today Then
        Debug.Print "The entered date is in the future."
    ElseIf dateToCompare < today Then
        Debug.Print "The entered date is in the past."
    Else
        Debug.Print "The entered date is today."
    End If
End If

CDate
Date
Format
Now