Regex to change case of letters

Note that you can easily use a regular expression search to capitalize certain strings in text. In this example we have a list of names, and we want to capitalize the last names of each person. Using NotePad++, we target strings with a first initial and then a period and a space ([A-Z]{1}\. ) and then in the second group any word containing uppercase or lowercase letters of any length ([A-Za-z]*). For search group # 1 enclosed in parentheses, the letter range is listed in the brackets, and then the letter count for the word is given in braces {}. We escape the period with a backward slash because a period has a separate meaning in regex. For the second group, we search for any uppercase or lowercase letter, with the asterisk signifying any number of characters.

([A-Z]\. )([A-Za-z]*)

In the replace field we can then reference the first group and the second group as \1 and \2. Adding \u before the second group signifier will capitalize the first letter.

\1\u\2

Switching \u to \l will make the first letter of the word in the second group lowercase.

Regex search to find and replace multiple strings

In order to find and replace multiple strings using regular expression you can use this format:

Find: (FindA)|(FindB)|(FindC)...

Replace: (?1ReplaceA)(?2ReplaceB)(?3ReplaceC)...

However if the operation is run this way it will not take word boundaries into consideration and will replace strings you search for which appear in the middle of other words. So if you run a search like this to capitalize the first names in a list of addresses:

. . .the search will not only capitalize 'Beth' but will also capitalize the string 'beth' in 'ElizaBeth'.

To prevent strings which are not words from being altered by the regex search use word boundaries around the searched for terms:

(\bbeth\b)|(\bmelissa\b)|(\bsusan\b)|(\bjennifer\b)

regex search to find files not containing a string

You can run a regular expression search which will find any files which do not contain a word or phrase that you designate.

In this example we have a set of text files, only one of which contains the word, 'panda'.

Using a text editor like NotePad ++ we run the following search to locate any files which do not have this string:

(?s)\A((?!panda).)+\z

. . . use the option to Find All using the Find in Files tool, and only the files in the folder in which you search which do not contain the string will be listed in the results pane.