cmd: Find first letter from a string

Question

I've no knowledge regarding cmd programming syntax. I have a text file containing user IDs which I need to delete using curl command and for that I need to extract first character of every user ID and then pass to the curl command. I know the curl command which I will require two variables:

1. 'UserID' - Read from the text file.
2. 'firstCharacter' - Extracting first character from the User ID.

Below is the code to fetch user IDs from symantecUsers.txt file:

@echo off
for /f "tokens=*" %%a in (symantecUsers.txt) do call :processline %%a
pause
goto :eof
:processline
echo %*
goto :eof
:eof

Please help me with extracting the first character from the read User IDs. Thanks.

Solution

You can get a substring by using the ~n,m syntax on a variable.

Setlocal EnableDelayedExpansion

for /f "tokens=1" %%a in (symantecUsers.txt) do (
    set userid=%%a
    echo The first character is !userid:~0,1!
)

Comments

[JosefZ]

Cross-posted stackoverflow.com/questions/36857098/…

[aschipfl]

So you are still working with MS-DOS, the OS from the 1980s?

[Jineet Vora]

@aschipfl haha... yeah have no other option... wanted to go with an easier way...

[Jineet Vora]

This works for echo but how do I store this in a variable?

[Berend]

The same way: set firstchar=!userid:~0,1!

[Berend]

@erreka That probably depends on how you define DOS :-)