I heard that you have to include stdio.h before calling printf. Why?
Q
I heard that you have to include stdio.h before calling printf. Why?
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A
So that a proper prototype for printf will be in scope.
A compiler may use a different calling sequence for functions which accept variable-length argument lists. (It might do so if calls using variable-length argument lists were less efficient than those using fixed-length.) Therefore, a prototype (indicating, using the ellipsis notation ``...'', that the argument list is of variable length) must be in scope whenever a varargs function is called, so that the compiler knows to use the varargs calling mechanism.
2015-06-17, 866👍, 0💬
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