There are many control flow blocks in Visual Basic 6 that help in executing some statements in a particular way. This lesson demonstrates the use of If-block.
The If control flow blocks provide a great way for decision making where one or more statements are executed depending upon a condition.
If-Then
In case of If-Then block, the condition is first checked. The condition can either be True or False. If it is True, the statements inside the If-Then block is executed. Otherwise, it does not execute the code in the If-Then block, the If-Then structure is skipped. It starts executing the statements just after the ‘End if’ phrase.
Syntax
If Condition Then
statements
End If
Example
To check if the number is positive.
Dim num1 As Integer
num1 = 30
If num1 > 0 Then
Print "The number is positive"
End If
output: The number is positive.
See the attached project IfThen to see this in action.
Single Line version of If-Then
Single line and single statement
If a > 0 Then b = 1
Single line and multiple statements
If a > 0 Then b = 1: c = 2
If-Else
An If-Else block has two parts. If the condition is True then the first part is executed, otherwise the control goes to the second part and starts executing the lines of statements in the second part of the If-Else block.
Syntax
If Condition Then
statements1
Else
statements2
End If
If Condition is true then statements1 will be executed and if Condition is false, statements2 will be executed.
See the attached project IfThenElse to see how this block works.
Example
To print the largest number.
Dim num1 As Integer, num2 As Integer
num1 = 30
num2 = 50
If num1 > num2 Then
Print num1
Else
Print num2
End If
Output: 50
The attached project LargestNumber allows you to see how If / then / else works with real data.
Single line version of If-Else
If a > 0 Then b = 1 Else b = 0
In the next lesson, you’ll learn more about the if-else statements.