Use replace regexp to add a sequence number at the beginning of a line

Suppose there is the following text

Google
Facebook
Amazon

Copy

You need to add a numerical sequence number at the beginning of the line , Become the following effect , What's a good way to ？

1. Google
2. Facebook
3. Amazon

Copy

replace-regexp This effect can be easily achieved ：

M-x replace-regexp RET ^ RET \,(1+ \#). RET

Explain it. ：

• ^ To match the beginning of a line

• \,(1+ \#). Replace with \, At the beginning, it means that this is a ELisp expression , among \# Indicates the current number of replacements , The default from the 0 Start , So I used 1+

Change the demand , If it is not a numerical serial number , It's the alphabet number , What can I do ？

a. Google
b. Facebook
c. Amazon

Copy

Replace with \,(char-to-string (+ ?a \#)). that will do .