Find out whether an environment variable contains a substring

Question

I need to find out if a certain environment variable (let's say Foo) contains a substring (let's say BAR) in a windows batch file. Is there any way to do this using only batch file commands and/or programs/commands installed by default with windows?

For example:

set Foo=Some string;something BAR something;blah

if "BAR" in %Foo% goto FoundIt     <- What should this line be? 

echo Did not find BAR.
exit 1

:FoundIt
echo Found BAR!
exit 0

What should the marked line above be to make this simple batch file print "Found BAR"?

Answer 1

Of course, just use good old findstr:

echo.%Foo%|findstr /C:"BAR" >nul 2>&1 && echo Found || echo Not found.

Instead of echoing you can also branch elsewhere there, but I think if you need multiple statements based on that the following is easier:

echo.%Foo%|findstr /C:"BAR" >nul 2>&1
if not errorlevel 1 (
   echo Found
) else (
    echo Not found.
)

Edit: Take note of jeb's solution as well which is more succinct, although it needs an additional mental step to figure out what it does when reading.

Answer 2

The findstr solution works, it's a little bit slow and in my opinion with findstr you break a butterfly on a wheel.

A simple string replace should also work

if "%foo%"=="%foo:bar=%" (
    echo Not Found
) ELSE (
    echo found
)

Or with inverse logic

if NOT "%foo%"=="%foo:bar=%" echo FOUND

If both sides of the comparision are not equal, then there must be the text inside the variable, so the search text is removed.

A small sample how the line will be expanded

set foo=John goes to the bar.
if NOT "John goes to the bar."=="John goes to the ." echo FOUND