RegEx to find and replace a word

Question

Hi all
I need a RegEx that allow me to search and replace
words chosen by me (eg. "some" instead of "same").
However, replacement should not happen if the word to replace
represents a resource (a file);
i.e. If some.jpg appears in the text, I don't have to replace anything.
How can I write such a thing?
Thanks in advance.

Luigi

Vulpes · Answer

You could do this using regex as follows: using System; using System.Text.RegularExpressions; class Program { static void Main() { string text1 = The some loathsome file; string text2 = The some file as some.jpg sometimes; string word = some; string replace = same; string regExp = @\b + word + @\b(?!\.\w{14}); text1 = Regex.Replace(text1 regExp replace); Console.WriteLine(text1); text2 = Regex.Replace(text2 regExp replace); Console.WriteLine(text2); Console.ReadKey(); } } The output is: The same loathsome file The same file as some.jpg sometimes Notice that 'some' is only replaced by 'same' if it's a complete word. So 'loathsome' and 'sometimes' are not changed. Notice also that the regex word boundary meta-character '\b' treats some.jpg as two words: 'some' and '.jpeg'. To avoid replacing 'some' here we need to use a negative lookahead so it will only be matched if it's not immediately followed by a dot and between 1 and 4 'word' characters.

Vulpes · Answer

Those two characters start a 'negative lookahead' the whole thing being placed in brackets. So it replaces 'some' with 'same' if it's a full word and not followed by \.\w{14} which is a dot and 1 to 4 letters digits or underscores. Notice that since dot is a regex meta-character (which matches any character) it needs to be 'escaped' with a back-slash when used literally.

Munesh Sharma · Answer

if you want to search particular word in a documnt then go here http://dotnet-munesh.blogspot.in/2014/05/searchhighlight-text-in-textbox-or.html

Luigi Z · Answer

Ok very clear. Thanks again Vulpes. L.

Luigi Z · Answer

Just a curiosity. What's mean ?! L

Luigi Z · Answer

Perfect thanks a lot Vulpes. L.