If 语句后面可以是一个可选的 Else 语句,当布尔表达式为 false 时执行。
If(boolean_expression)Then
'statement(s) will execute if the Boolean expression is true
Else
'statement(s) will execute if the Boolean expression is false
End If
如果布尔表达式的计算结果为 true,则将执行 if 代码块,否则将执行 else
代码块。
Dim a As Integer = 100 If (a < 20) Then Proj.MsgDebug.Add("a is less than 20") Else Proj.MsgDebug.Add("a is not less than 20") End If Proj.MsgDebug.Add("value of a is : {0}", a) '返回结果:a Is Not less than 20 '返回结果:value Of a Is : 100 |
If(boolean_expression 1)Then
' Executes when the boolean expression 1 is true
ElseIf( boolean_expression 2)Then
' Executes when the boolean expression 2 is true
ElseIf( boolean_expression 3)Then
' Executes when the boolean expression 3 is true
Else
' executes when the none of the above condition is true
End If
Dim a As Integer = 100 If (a = 10) Then Proj.MsgDebug.Add("Value of a is 10") ' ElseIf (a = 20) Then Proj.MsgDebug.Add("Value of a is 20") ' ElseIf (a = 30) Then Proj.MsgDebug.Add("Value of a is 30") Else Proj.MsgDebug.Add("None of the values is matching") End If Proj.MsgDebug.Add("Exact value of a is: {0}", a) '返回结果:None Of the values Is matching '返回结果:Exact value Of a Is: 100 |