#10 – The Return Value from Main() Sets ERRORLEVEL Variable in Windows
June 27, 2010 9 Comments
If your Main() function returns an integer value, you can check that value in the calling program or script using the ERRORLEVEL environment variable. By convention, a return value of 0 indicates success and any other value indicates an error. Below is a sample .bat file that calls a program called MyProgram and then checks the return value.
@echo off
MyProgram
IF "%ERRORLEVEL%" == "0" goto OK
:NotGood
echo Bad news. Program returned %ERRORLEVEL%
goto End
:OK
echo Everything A-OK
:End
About Sean
2,000 Things You Should Know About C# 
i didnt get it…how it works… ???
@echo on
2000CSharp
IF “%ERRORLEVEL%” == “0” goto OK
:NotGood
echo Bad news. Program returned %ERRORLEVEL% >>log.txt
goto End
:OK
echo Everything A-OK>>log.txt
:End
The ERRORLEVEL environment variable is automatically set by Windows to contain the return value of your program. In the example above, if your program returned a value of -1, the script would echo “Bad news. Program returned -1”. If your program returned 0, the script would echo “Everything A-OK”.
ya i understood the code and but practically how to implement it to get that echo sound ?
Echo will echo out to the console any string that you give it. It’s a DOS command. You can experiment with it in a command prompt.
didn’t understand the batch script, as it only runs the program and nothing else happens even if i put errorlevel 1 instead of 0
If the %ERRORLEVEL% variable in the .bat file will contain the value that you program returned. So if you exit your program with a statement like “return 5”, then the %ERRORLEVEL% variable will contain the value of 5 after invoking the program.
Sorry but i still don’t understand how to implement this practically. Plz explain.
Maybe you could expand on your question. What are you trying to do?