1. Practical Programming COMP153-08A Lecture 4:Strings & Formatting

2. Tools -> Options

3. Programming So Far First: Controls, Properties, Events Second: Types and Arithmetic Third: Variables and some Input/Output Today: –Strings & Formatting

4. Consider this code Dim x As Integer x = Val(TextBox1.Text) TextBox2.Text = Str(x) Use x = 12.49 and x = 12.51

5. Formatting Input To be more “precise” we use: Convert: –Dim x As Integer –x = Convert.ToInt32(TextBox1.Text) –We can ToDouble, ToInt16 (short), ToSingle, ToDouble.

6. Example Dim x, y As Integer x = Convert.ToInt32(TextBox1.Text) y = Convert.ToInt32(TextBox2.Text) Label1.Text = Str(x) & Str(y) Label2.Text = Str(x) + Str(y) Label3.Text = x.ToString + y.ToString Label4.Text = x.ToString & y.ToString

7. Example in action

8. Formatting output Numeric –Generally: VARNAME.ToString(formatString) Examples – currency format (“c”) Dim price As Single price = Val(TextBox1.Text) Label1.Text = price.ToString("C")

9. Price Example

10. Decimal Places Change the “C” to “N2” (for two decimal places) Dim price As Single price = Val(TextBox1.Text) Label1.Text = price.ToString(“N2")

11. Percentage Change to “P” Dim price As Single price = Val(TextBox1.Text) Label1.Text = price.ToString(“P")

12. Strings Strings have many associated methods –Dim s As String = “I am a string” –MessageBox.Show(s.Length) Strings and spacing –Dim s As String = “123” –Label1.Text = s –Label2.Text = s.PadLeft(5) –Label3.Text = s.PadLeft(10) –Can also use PadRight

13. Padding to total length

14. Bigger Example

15. Solution Dim x, y As Integer x = Val(TextBox1.Text) y = Val(TextBox2.Text) Label1.Text = "Mod of " & x & " " & y & " = " & x Mod y Label2.Text = "Exp of " & x & " " & y & " = " & x ^ y Label3.Text = "Div of " & x & " " & y & " = " & x \ y Label4.Text = "Concat of " & x & " " & y & " = " & Str(x) + Str(y)

16. Test on Friday 9-11 in Lab 3 9 questions (40 marks) Topics –Computer components (4) –Controls (2) –Setting properties (4) –Setting properties 2 (4) –Events (6) –Arithmetic 1 (4) –Types (4) –Arithmetic 2 (10) –Formatting (2)

17. THE END of the lecture