Visual Basic provides several functions to format and retrieve parts of
strings.
Joining strings with &
You can use the & operator to join two strings. This operation is
called concatenation. For example:
FirstString = "This string has " SecondString = "been concatenated!" NewString = FirstString & SecondString
NewString would contain "This string has been concatenated!".
Note that you need a space at the end of the first string or at the beginning of the
second string, so that there is a space between "has" and "been".
Left$, Right$
These functions retrieve part of the string. The Left$ function returns
characters from the left hand side, and the Right$ function returns characters from the
right hand side. This is what they do:
MyString = "This is a nice long string" LeftString = Left$(MyString, 7) RightString = Right$(MyString, 6)
LeftString contains the text "This is", and RightString contains
the text "string".
Syntax
Left$(string, length) Right$(string, length)
Mid$
This function is used to retrieve part of a string, much like Left$ and
Right$. This is how it is used:
MyString = "This is a nice long string" NewString = Mid$(MyString, 6, 21)
NewString now contains "is a nice long string"
Syntax
Mid(string, start[, length])
UCase$, LCase$
Use these two functions to convert a string to entirely upper case or
entirely lower case characters. This is very useful if you want to do a case insensitive
search, or if a password is not case sensitive. For example:
MyString = "This is a nice long string" UCaseString = UCase$(MyString) LCaseString = LCase$(MyString)
UCaseString contains "THIS IS A NICE LONG STRING", and
LCaseString contains "this is a nice long string". This can be used practically:
PasswordAttempt = "MyPaSs"
ActualPassword = "mYpAsS"If PasswordAttempt = _
ActualPassword Then succeeded1 = True
Else
succeeded1 = False
End If
If UCase$(PasswordAttempt) = UCase$(ActualPassword) _
Then succeeded2 = True
Else
succeeded2 = False
End If
In this case, succeeded1 would be False, and suceeded2 would be True. This
is because the two actual passwords do not equal each other, but when they are both
converted into upper case, they do equal each other.
Syntax
Mid(string, start[, length])
String$
This function returns a string of repeating characters. For example,
String$(20, "*"), would return "********************".
Syntax
String(number, character)
Len
This function returns the length of a string. It is useful in a For…Next
loop to do something to each character in a string. For example:
mystring = "Hello world!" mylen = Len(mystring) For charnum = 1 To mylen Debug.Print Mid$(mystring, charnum, 1) Next
Here you will get H, e, l, l, o, , w, o, r, l, d, !, printed out in the
debug widow, with each character on a separate line. mylen returns 11 because the length
of the string is 11.
Syntax
Len(string)
Watch out soon for advanced string
functions, where we will show you how to do search and replace facilities, and look at
the other string functions.
