Just out of curiosity I want to know what language was used to write Windows itself.
closed as not a real question by Synetech, Canadian Luke, 3498DB, Joe Taylor, Diogo Aug 9 '12 at 12:19
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We use almost entirely C, C++, and C# for Windows. Some areas of code are hand tuned/hand written assembly.
Well, the Windows kernel is still almost entirely C. However, there are different aspects that use C++, say some parts of the shell and so forth. The core is C. Other languages, perhaps even .NET might be used in some corners for certain applications but C is the OS language of choice in Windows.