Add character to every number via Regex in Notepad++

I have a very basic question which i just can not get my head around. I do have a text document like this:

This is 5 a test!
This 3 is a test!
This is a 9 test!

and i want it to look like this:

This is 5c a test!
This 3c is a test!
This is a 9c test!

Means i want to add a 'c' to every number i find. I tried this:

Find what: [0-9]+]
Replace with: $1c
Search Mode: Regular expression

but i am obviously doing something wrong because it is not working. Help would be appreciated. Thank you!


You almost got it right.

You want to search for ([0-9]+)
And replace that with $1c

You use ( ) to create a capture group, so $1 works.

Alternatively, you can replace with $0c instead, then you don't need to use a capture group.


  • Ctrl+H
  • Find what: \d+
  • Replace with: $0c
  • check Wrap around
  • check Regular expression
  • Replace all

Result for given example:

This is 5c a test!
This 3c is a test!
This is a 9c test!