Function call mechanism in c

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Alternatively, the answer will be in your course notes and if you'd bothered to turn up for class you would know this.

Read the paragraph before the question section

Meindert

This depends on the processor and the compiler. Many processor makers publish the specs for a binary call compatibility standard. This ensures that libraries made by various compilers can be interoperable. Conformance is usually voluntary, of course.

If you make a compiler and you don't want to work with libraries made by others then its entirely up to you how you define the calling conventions.