How can I get how many times a string occurs in a textbox?
I thought the find function would return the number of times found but it seems to return the location of it.
id be interested to know the performance of this, but +1 for clear simple code.
Matt Joslin
2009-12-28 13:10:34
thank you, what do I have to import to use it?
Jonathan
2009-12-28 13:16:08
`Import System.Text.RegularExpressions`Regex provides best performance for simple searches, especially if you use the `Compiled` flag and precreate the regex object. But I never benchmarked this.
Aviad P.
2009-12-28 13:16:32
This will not work as expected if `inputString` contains special characters. You need to call `Regex.Escape`.
SLaks
2009-12-28 13:26:49
It worked, except it is count not length at the end.
Jonathan
2009-12-28 13:29:18
@Jonathan: If you use this, change it to `Regex.Matches(textBox1.Text, Regex.Escape(inputString)).Count`.
SLaks
2009-12-28 13:31:47
I'm sorry, fixed.
Aviad P.
2009-12-28 13:34:41
A:
You can call Split, like this:
(" " + textBox1.Text + " ").Split(New String() { inputString }, StringSplitOptions.None);
Alternatively, you can keep calling IndexOf with the startIndex equal to the previous call's return value + 1 until it returns -1.
SLaks
2009-12-28 13:25:56
I'm sorry but this is about twice as slow as regex, tested and benchmarked. Code at http://pastebin.com/m52d69edc
Aviad P.
2009-12-28 13:47:44
Even without precompiling the regex, and with using Regex.Escape on each call, the regex is still twice as fast as the Split way, plus you can divine additional information from the regex such as where the matches are located in the original string.
Aviad P.
2009-12-28 14:00:59
Few things can beat the performance of a well-implemented regular expression search engine, provided the pattern and the text are not known or indexed in advance.
Aviad P.
2009-12-28 14:20:20