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This article introduces the relevant knowledge of "the usage of VBS conditional sentences". In the operation process of actual cases, many people will encounter such difficulties. Next, let Xiaobian lead you to learn how to deal with these situations! I hope you can read carefully and learn something!

Conditional statements and loop statements control the flow of scripts. Conditional statements allow you to write VBScript code that performs judgments and repeated operations. The following conditional statements are available in VBScript:

If... Then... Else statement

Select Case statement

Use If... Then... Else to judge

If... Then... The Else statement evaluates whether a condition is True or False and specifies which statement to run based on the evaluation result. Typically, conditions are expressions that compare values or variables using comparison operators. For more information about comparison operators, see Comparison Operators. If... Then... Else statements can be nested as desired.

Run statement when condition is True

To run a single-line statement when the condition is True, use If... Then... Single-line syntax for Else statements. The following example demonstrates single-line syntax. Note that the keyword Else is omitted from this example.

Sub FixDate() Dim myDate myDate = #2/13/95# If myDate < Now Then myDate = Now End Sub

To run multiline code, you must use multiline (or block) syntax. The multiline (or block) syntax contains an End If statement, as follows:

Sub AlertUser(value) If value = 0 Then AlertLabel.ForeColor = vbRed AlertLabel.Font.Bold = True AlertLabel.Font.Italic = True If End Sub Runs certain statements when the condition is True and False, respectively

You can use If... Then... An Else statement defines two executable statement blocks: one statement block runs when the condition is True, and another statement block runs when the condition is False.

Sub AlertUser(value) If value = 0 Then AlertLabel.ForeColor = vbRed AlertLabel.Font.Bold = True AlertLabel.Font.Italic = True Else AlertLabel.Forecolor = vbBlack AlertLabel.Font.Bold = False AlertLabel.Font.Italic = False End If End Sub Judge multiple conditions

If... Then... A variant of the Else statement that allows you to choose from multiple conditions is to add an ElseIf clause to extend the If... Then... Else statements enable you to control program flow based on a variety of possibilities. For example:

Sub ReportValue(value) If value = 0 Then MsgBox value ElseIf value = 1 Then MsgBox value ElseIf value = 2 then Msgbox value Else Msgbox "Value out of range! " End If

You can add any number of ElseIf clauses to provide multiple choices. Using multiple ElseIf clauses often becomes cumbersome. A better way to select among multiple conditions is to use the Select Case statement.

Use Select Case to judge

The Select Case structure provides an If... Then... A variation of the ElseIf construct, which allows you to select one of several statement blocks to execute. The Select Case statement provides the same functionality as the If... Then... Else statements are similar, but can make the code simpler and easier to read.

The Select Case construct begins with a simple test expression that evaluates only once. The result of the expression is compared to the value of each Case in the structure. If there is a match, the statement block associated with the Case is executed. Example code is as follows:

Select Case Document.Form1.CardType.Options(SelectedIndex).Text Case "MasterCard" DisplayMCLogo ValidateMCAccount Case "Visa" DisplayVisaLogo ValidateVisaAccount Case "American Express" DisplayAMEXCOLogo ValidateAMEXCOAccount Case Else DisplayUnknownImage PromptAgainEnd Select

Note that the Select Case construct evaluates only one expression at the beginning (only once), whereas If... Then... The ElseIf construct evaluates expressions for each ElseIf statement, which can vary. You can use the Select Case construct instead of If... only if each ElseIf statement evaluates the same expression. Then... ElseIf structure.

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