* VB-CODE (1)
Tip 151: Finding Whole Words in a Text Box Control
September 5, 1995
When you design a Microsoft? Visual Basic? application, you can add a Text
Box control to your project. The Text Box control lets a user type text
that can be manipulated by your program. This article explains how you
can add a word-search function to your program.
Using the InStr Function
The Text Box control provided in Microsoft? Visual Basic? acts like a
miniature word-processing program. As new text is typed, it is appended
to the text that already exists in the control. Your user can edit
existing text or delete text that is no longer needed. However, that
is the extent of the word-processing capability of the Text Box. You
can, however, use the InStr function to add your own search function
to find words in a Text Box control.
In the example program below, you use a FindMatch function to search the
Text Box control for a specific word. A message box is displayed telling
you whether or not the target word was found.
You can use the InStr function to isolate a specific piece of text within
a larger piece of text. When the search finds a specific word match, the
InStr function identifies the target text.
It is a simple task to direct the InStr function to search for a
particular word in the Text Box control. Let's assume you want to
see whether the word dog is in the string, "He owns a cat and a dog".
To do this, you tell InStr to search for the target word by issuing a
statement such as:
X = InStr("He owns a cat and a dog", "dog")
Because the word dog actually exists in the sentence, InStr will report
where it found the string dog. In the example program below, you assume
that a word is defined by a space character, both before and after the
word. However, if the string ends with a period character, then the InStr
function will not find the word dog. This is because that word is actually
the characters d-o-g-period.
Therefore, you must take punctuation characters into account when you
write a word-search function. In the example program below, you isolate
each word that is surrounded by space characters. In addition, you
isolate words that end with a linefeed, carriage return, comma, period,
or space. This enables you to determine whether a word exists in the Text
Box control, regardless of punctuation that may or may not be appended to
the end of the word.
This program shows how to search a Text Box control for whole words.
1. Create a new project in Visual Basic. Form1 is created by default.
2. Add a Text Box control to Form1. Text1 is created by default. Set
its MultiLine property to True.
3. Add a Label control to Form1. Label1 is created by default. Set
its Caption property to "Find word:".
4. Add a second Text Box control to Form1. Text2 is created by default.
5. Add a Command Button control to Form1. Command1 is created by default.
6. Add the following code to the Click event for Command1:
Private Sub Command1_Click()
Dim X As Integer
X = FindMatch(Text1.Text, Text2.Text)
If X = 0 Then
MsgBox "Word not found"
MsgBox "Word found"
7. Create a new function called FindMatch. Add the following code to
Function FindMatch(Str1 As String, Str2 As String) As Integer
Dim Match As Integer
Dim Char1 As String
Dim Char2 As String
Match = InStr(Str1, Str2)
If Match <> 0 Then
Char1 = Mid$(Str1, Match - 1, 1)
If Codes(Char1) Then
Char2 = Mid$(Str1, Match + Len(Str2), 1)
If Codes(Char2) Then
FindMatch = True: Exit Function
FindMatch = False
8. Create a new function called Codes. Add the following code to this
Function Codes(PuncStr As String) As Integer
If PuncStr = "," Or PuncStr = "." Or PuncStr = " " Or PuncStr = Chr(10) Or PuncStr = Chr(13) Or PuncStr = Chr(9) Then
Codes = True
Codes = False
Run the example program by pressing F5. Type some text in the first Text
Box control. In the second Text Box control, type a word that you want
to search for in the first Text Box. Click the command button to execute
the search routine. A message box is displayed, telling you whether the
target word (in Text2) was found in the Text Box (Text1).
"InStr function." (Development Library, Product Documentation,
Languages, Visual Basic 4.0 Professional and Enterprise Editions,
Language Reference, AZ Reference)