without cctype header also can work?

I just use the header file <iostream>, but when I use toupper, it works, why?
(I use the VC++ 6.0)
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another question:
I've dowloaded a Visual Assist Cracked version, it contains a exe file and a crack.exe, I don't know to setup the extension to which path, help.
1. Maybe iostream includes cctype internally.
2. Visual Assist X installer does not require any configuration, it automatically detects your Visual Studio version and instalation path.
why I see the answer always "maybe" in iostream? Is that mean when I use another compiler, If I don't #include <cctype>, the toupper won't work?
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