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Conditional Logic in Visual Basic Programming
This document discusses conditional logic in Visual Basic programming. It provides examples of using If/Then statements to execute code based on whether a condition is true or false. Specifically, it demonstrates: - Using If/Then to check for equality and show a message box if two variables are equal. - Using If/Then/Else to check for equality and show different message boxes depending on if the variables are equal or not equal. - Using If/Then/ElseIf/Else/End If to check multiple conditions and show different message boxes depending on which condition is met.
Conditional Logic in Visual Basic Programming
- 1. Lesson 3 of8 Visual Basic Programming 1 of 4 Lesson 3: Conditional Logic Author: Kasun Ranga Wijeweera Email: krw19870829@gmail.com Date: 2020 April 29 Look at the code segment given below. Dim x, y As Integer x = 5 y = 5 If x = y Then MessageBox.Show (“Equal”) Execution of the above code segment displays a message box with text “Equal”. The equals sign shown in red color works as the Equality Operator. If the value of x equals to the value of y then the code fragment x = y returns True. Otherwise the code fragment returns False. If…Then statement was used in the code segment above. A <<condition>> should be written between If and Then parts. The code fragment in the right side of the Then part is executed only if the <<condition>> returns True. Now look at the code segment given below. Dim x, y As Integer x = 5
- 2. Lesson 3 of8 Visual Basic Programming 2 of 4 y = 6 If x = y Then MessageBox.Show (“Equal”) Execution of the above code segment does not display the message box as the <<condition>> returns False. Only a single line of code can be included after Then part when using If…Then statement. Therefore, If…Then…End If statement should be used in order to have more than a single line of code after Then part. Now look at the code segment given below. Dim x, y As Integer x = 5 y = 5 If x = y Then MessageBox.Show (“Equal”) MessageBox.Show (“x is equal to y”) End If Execution of the above code segment displays two message boxes each with texts “Equal” and “x is equal to y” respectively. Look at the code segment given below that demonstrates the usage of If…Then…Else statement. Dim x, y As Integer x = 5 y = 5
- 3. Lesson 3 of8 Visual Basic Programming 3 of 4 If x = y Then MessageBox.Show (“Y”) Else MessageBox.Show (“N”) Execution of the above code displays “Y” in a message box since the condition is true. Execution of the code given below displays “N” in a message box since the condition is false. Dim x, y As Integer x = 5 y = 6 If x = y Then MessageBox.Show (“Y”) Else MessageBox.Show (“N”) If…Then…Else…End If statement should be used when there are more than a single line of code to execute if the condition is either true or false. Look at the code segment given below. Dim x, y As Integer x = 5 y = 5 If x = y Then MessageBox.Show (“Equal”) MessageBox.Show (“x is equal to y”) Else MessageBox.Show (“Not equal”) MessageBox.Show (“x is not equal to y”) End If Execution of the above code displays two message boxes each with texts “Equal” and “x is equal to y” respectively as the condition is true. Now look at the code segment given below.
- 4. Lesson 3 of8 Visual Basic Programming 4 of 4 Dim x, y As Integer x = 5 y = 6 If x = y Then MessageBox.Show (“Equal”) MessageBox.Show (“x is equal to y”) Else MessageBox.Show (“Not equal”) MessageBox.Show (“x is not equal to y”) End If Execution of the above code segment displays two message boxes with texts “Not equal” and “x is not equal to y” respectively as the condition is false. If…Then…ElseIf…Else…End If statement can be used when there are multiple conditions. Look at the code segment given below. Dim x As Integer = 18.76 If x < 10 Then MessageBox.Show (“x < 10”) ElseIf x < 20 Then MessageBox.Show (“10 <= x < 20”) ElseIf x < 30 Then MessageBox.Show (“20 <= x < 30”) Else MessageBox.Show (“x >= 30”) End If