Batchography: Number counting in Batch files

This is yet another article about Batch files. In this article, I am going to show you how to do number counting loops in Batch files.

For more advanced Batch scripting topics, please grab a copy of the Batchography book.

In Batch files, to achieve number counting, you have to use /L switch with the FOR keyword to start a counting loop.

The following are to two syntaxes that you can use from the command line or from inside the script respectively:

FOR /L %variable IN (start, step, end) DO command [command-parameters]

And from inside a script just prefix the count variable with an extra “%”:

FOR /L %%variable IN (start, step, end) DO command [command-parameters]

Please note the most important arguments to pass to the FOR /L:

• variable: The variable name should be a single character (case sensitive) and should be prefixed with a single “%” or two of them “%%” depending on where the FOR /L is invoked from.
• start: the starting count number.
• step: the number of steps taken after each iteration. The steps can be a negative or a positive number.
• end: at which number should the counting stop (the ending number is included in the counting).
• command: The command to execute which could be a single line command or a composite command. Please refer to the Batchography book for information on composite commands.

Let’s take a simple (based on the for-count.bat script) example:

FOR /L %%i IN (10, 1, 20) DO (

   ECHO i=%%I
)

This simple script starts counting from 10 until 20 while incrementing the counter just once per iteration. Let’s run it and observe its output:

C:\Batchography>simple-count.bat
i=10
i=11
i=12
i=13
i=14
i=15
i=16
i=17
i=18
i=19
i=20

C:\Batchography>

It is also possible to count backwards by changing the parameters by starting from a higher number, down to a lower number and specifying a negative step argument like this:

@echo off
FOR /L %%i IN (20, -1, 10) DO (
   ECHO i=%%i
)

…and the output is:

C:\Batchography>simple-count-backwards.bat
i=20
i=19
i=18
i=17
i=16
i=15
i=14
i=13
i=12
i=11
i=10

C:\Batchography>

That’s it! Simple and straight to the point. You might also like:

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