How to split string without for loop in batch file

Question

I want to split a string in two parts, without using any for loop.

For example, I have the string in a variable:

str=45:abc

I want

Answer 1

Here's a solution without nasty tricks for leading piece

    REM accepts userID@host
    setlocal enableDelayedExpansion
    set "str=%1"
    set "host=%str:*@=%"
    for /F "tokens=1 delims=@" %%F IN ("%str%") do set "user=%%F"
    echo user@host = %user%@%host%
    endlocal