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I cannot understand what the following means "ISAPI applications can be written using any language which allows the export of standard C functions, for instance C, C++, Delphi." What is "allowing export of C/C++/Delphi functions" ?

P.S. I am very very new.

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2 Answers 2

It means declaring the functions in one module in a manner that allows them to be called by another module - making them 'public', calling them via 'extern' declarations, and so on. The terminology varies from language to language.

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THe C language has a very well defined stack frame and calling convention for it's functions. It has been stable for many years, and is probably the most widely used interface in computing today - Windows API calls, and Unix/Linux System calls use the C calling convention. Many (most?) languages can build a function that has the C stack frame, and call fucntions using the C stack frame. In most cases, this requires the compiler to be told not to use it's native calling convention.

The "allow exporting...." statement is a way of saying that if the language can make and/or use a C style stack frame, it will work.

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Not literally true, but a reasonable approximation. On pretty much every platform, there is a consensus what C stack frames look like, and what the C calling convention is. This is commonly called the C ABI. However, the C ABI for Sparc/Solaris isn't the same as the C ABI for x86/Windows. It can't be; the C ABI for Sparc uses CPU registers that x86 just doesn't have. –  MSalters Aug 4 '11 at 11:17
    
I never though that it might be possible to call a function in a SPARC application directly from a Windows application. –  mattnz Aug 5 '11 at 1:12
    
It's not, of course, but it does contradict your statement that there is a well-defined calling convenction for C. Oh, and Windows famously does not use the C calling convention. –  MSalters Aug 5 '11 at 7:38

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