CS4 – lecture 6

1. CS4 –lecture 6 Wednesday, Jan 19, 2011 Roxana Gheorghiu

2. Numbers and Arithmetic Operations • Standard Arithmetic Operations: • Addition (+) • Subtraction (-) • Division (/) • Multiplication (*) • Exponentiation (^) • Level of precedence for arithmetic operations:

3. Numbers and Arithmetic Operations • Standard Arithmetic Operations -Level of precedence for arithmetic operations: • Addition (+) • Subtraction (-) • Division (/) • Multiplication (*) • Exponentiation (^)

4. Numbers and Arithmetic Operations • Level of precedence for arithmetic operations: • Addition (+) • Subtraction (-) -LEVEL 3 • Division (/) • Multiplication (*) -LEVEL 2 • Exponentiation (^) –LEVEL 1 • NOTE: • 1/0 = Infinity • Math.Sqrt(-4) =NaN (Not a Number)

5. Built-In Functions • Modulo : x Mod y =the reminder when m is divided my n • Ex: 20 Mod 2 =0 • 15 Mod 4 =3 • Square root: Math.Sqrt( #number) • Ex: Math.Sqrt(9) =3

6. Built-In Functions (cont.) • The greatest integer less than or equal to a number: Int(#number) • Ex: Int(2.7) =2 • Int(-2.7) =-3 • Rounding a number to r decimal places: Math.Round(#number, #r) or Math.Round(#number) • Math.Round(2.14 , 1) =2.1 • Math.Round(2.67) =3

7. Assignment Statement Var= expression • (1) Dim myNumber as Double myNumber =5.21 • (2) Dim myNumber as Double =5.21 NOTE: Dim x as Integer =3, y as Double =5.3

8. String Properties and Methods Dim str as String =“ My own String ” • Length() =returns the number of characters in the string • str.Length ->19 • ToUpper() =returns the string with letters capitalized • str.ToUpper() ->” MY OWN STRING “ • ToLower() =returns the string with all letters in lowercase format • Str.ToLower() -> “ my own string “ • Trim() =returns the string with all spaces removed from the front and back of the string • str.Trim() -> “My own String”

9. String Properties and Methods Dim str as String =“My own String ” Dim str2 as String = “own” • Substring (m,n) =the substring that starts at position m and its n characters long • IndexOf(newString) • str.IndexOf(str2) =str.IndexOf(“own”) returns: 6 • str.Substring(0,5) returns: “ My” • Clear() =creates an empty string • str.Clear() • str.Txt=“”

10. String Properties and Methods • CStr(number)or number.ToString • converts a number into a string • CInt(string) • converts a String into an Integervalue • CDbl(string) • converts a String into a Doublevalue • & • used to concatenate two strings • str =“One” ; str1 =“ and two” • str & str1 returns: “One and two” • _ • the continuation character

11. Input Data from a Text Box stringVar =textBox.Text Ex: Dim str as String str =txtName.Text • If the input data will be used in a MATH expression you will need first to convert it to Double or Integer and then use it

12. Input Data from Dialog Box stringVar = InputBox(prompt, title) Ex: Dim name as String Dim prompt, title asString prompt =“Please give a name” title =“Input box for a name” name =InputBox(prompt, title)

13. Output Data Using a Message Box MsgBox(prompt, button, title) Ex: MsgBox (“Congratulation !”, 0, “Result Window”) OR MsgBox (“Congratulation !”) -> in this case the title is the same string as the name of the main window Note:check*Dailly Schedule* on www.cs.pitt.edu/~roxana/cs4/ for a complete list of possible values for variable button

14. Application (1) Write a VB program that asks a name as input and it will copy that name in a list. (2) Write a VB program that asks a name as input and it will copy the first name in one list and the last name in another list (3) Continue exercise (2) by adding a new button Del, that will delete an entry selected from any list.