Windows batch script set variable

So now we have a way to check if a "hidden" variable still has its dynamic system value, or a static "custom" value:. Command Extensions X. Command extensions enable extra features in NT shells. By default command extensions are enabled.

Note that the variable! This is double expansion of the variable i. Thus it increases to 2 on the 2nd pass through the loop, and to 3 on the 3rd pass. Thus the string echoed to the screen alters with each pass. When multiple variables are defined at the beginning of the batch, a short definition form may be used by employing a replacement string. It is possible to create a set of variables that can act similar to an array although they are not an actual array object by using spaces in the SET statement:.

It is also possible to declare your variable using indexes so you may retrieve specific information. This will create multiple variables, with the illusion of an array:. Note that in the example above, you cannot reference var without stating what the desired index is, because var does not exist in its own. There are two types of variables in batch files. One is for parameters which can be passed when the batch file is called and the other is done via the set command.

Batch scripts support the concept of command line arguments wherein arguments can be passed to the batch file when invoked. Following is a screenshot of how this would look in the command prompt when the batch file is executed. Following is the syntax of the set command. System-wide variables, known as environmental variables, use uppercase names. It would be a bad idea to overwrite these dynamic variables.

The example below prints the current value of the variable foo to the console output. The SET command with no arguments will list all variables for the current command prompt session. By default, variables are global to your entire command prompt session. This example demonstrates changing an existing variable named foo within a script named HelloWorld. There are a few special situations where variables work a bit differently. There is also a variable syntax using!