String Processing

1
String Processing

• We have established that a string variable may be
  used to store alphanumeric data, e.g.
• Dim MyString as String
• MyString "This has numbers 1234 and text!"

2
Concatenation

• We have seen how we can concatenate smaller
  strings to form larger strings
• Dim Var1 as String
• Dim Var2 as String
• Dim Var3 as String
• Var1 "Hello"
• Var2 "World"
• Var3 Var1 " " Var2
• Resulting in Var3 containing "Hello World".

3

• Two new things we are going to look at today are
  are
• Splitting Strings
• Padding Strings

4
How are Strings Split?

• To split a string, we use a method of a string
  variable called SubString.
• E.g.
• StringName.SubString(Start, Length)

5
SubString Version 1

• The following code splits a string at a start
  position returning a specified number of
  characters
• Dim String1 as String
• Dim String2 as String
• String1 "Hello World"
• String2 String1.SubString(6,5)
• At the end of this code String2 would contain
  the text "World".

6
Questions

• Given the following text
• Hello World
• what sub strings are returned by the following
• SubString(0,5)
• SubString(1,1)
• SubString(11,5)
• What substring code would need to be written to
  extract the text "Hell" from the above string?

7
SubString version 2

• Essentially what this does is tell VB to return
  the right hand part of a string from a specified
  position, so
• Dim String1 as String
• Dim String2 as String
• String1 "Hello World"
• String2 String1.SubString(6)
• Would start at position 6 "W" and return the rest
  of the string "World".

8
Padding Strings

• PadRight
• PadRight in it's simplest form accepts one
  parameter which specifies how large the string
  should be "padded" to.
• For example
• The text "hello" padded right 10 would produce
• "hello "

9

• What do you suppose the following code does?
• Dim String1 as String
• Dim String2 as String
• String1 "hello"
• String2 String1.PadRight(20,"")
• What happens with the following code?
• Dim String1 as String
• Dim String2 as String
• String1 "hello"
• String2 String1.PadRight(2)