May 4th, 2006

Doing quick arithmetic from the command prompt

The command processor CMD.EXE comes with a mini-calculator that can perform simple arithmetic on 32-bit signed integers:

C:\>set /a 2+2
4
C:\>set /a 2*(9/2)
8
C:\>set /a (2*9)/2
9
C:\>set /a "31>>2"
7

Note that we had to quote the shift operator since it would otherwise be misinterpreted as a “redirect stdout and append” operator.

For more information, type set /? at the command prompt.

Author

Raymond has been involved in the evolution of Windows for more than 30 years. In 2003, he began a Web site known as The Old New Thing which has grown in popularity far beyond his wildest imagination, a development which still gives him the heebie-jeebies. The Web site spawned a book, coincidentally also titled The Old New Thing (Addison Wesley 2007). He occasionally appears on the Windows Dev Docs Twitter account to tell stories which convey no useful information.

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