How to Create a Function in Batch Script

You need not write a code for the same task again and again if you create a function for that specific task. This article will discuss how we can create a function in Batch Script.

Create a Function in Batch Script

The general format for creating a function is shown below.

:function_name

And the general format to call this function is by using a CALL keyword with :function_name, like the one below.

CALL :function_name

Now let’s see some examples with proper explanations to make this easier to understand.

In our below example, we just created a function that prints the message Hello! It's the function.... Our code for this example will look like this:

@echo off
CALL :showmessage
EXIT /B %ERRORLEVEL%

:showmessage
ECHO Hello! It's the function...
EXIT /B 0

You can notice that we wrote the line EXIT /B %ERRORLEVEL%. This line aims to exit the program after the function has done its job; otherwise, the program will continue executing the function.

And the line EXIT /B 0 was created to exit the function.

After running the code, you will get the below output.

Output:

Hello! It's the function...

Call a Function With Parameters

In our next example, we will call a function with parameters.

The general format for calling a function is shown below:

CALL :function_name %parameter%

And the parameter can be accessed inside the function by using the index of parameters like %~1.

Our code for the example will look like this:

@echo off
SET FuncVar=10
CALL :showvar %FuncVar%
EXIT /B %ERRORLEVEL%

:showvar
ECHO Your passed variable is %~1
EXIT /B 0

In the example, we declared a variable named FuncVar with the value 10. After that, we called the function and passed this variable as a parameter.

In the function, we just printed the parameter passed to the function. Now the output will be like the following.

Output:

Your passed variable is 10

Call a Function With Multiple Parameters

When working with multiple parameters, you have to follow the format given below:

CALL :function_name %parameter1% %parameter2% %parameter3%

In our next example, we passed multiple variables as parameters in the function. The example code will be,

@echo off
SET FuncVar1=10
SET FuncVar2=50
CALL :showvar %FuncVar1% %FuncVar2%
EXIT /B %ERRORLEVEL%

:showvar
ECHO Your 1st parameter is %~1
ECHO Your 2nd parameter is %~2
EXIT /B 0

You can notice that we accessed two parameters depending on the index of the parameters like %~1 and %~2. After running the code, you will get the following output.

Output:

Your 1st parameter is 10
Your 2nd parameter is 50