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maths_fan
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 Posted: Fri Feb 27, 2004 2:49 pm Post subject: function as a parameter |
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I know that the correct is when I write:
void g(int);
void f(void*);
.............
f(g);
But my compiler (Visual C++ 6 and .NET) don't mind when I use it like this:
f(void g(int a));
Is it correct by standard of C++ to write like this?
Thanks in advance.
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Ben Hutchings
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| Posted: Sat Feb 28, 2004 3:43 am Post subject: Re: function as a parameter |
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maths_fan wrote:
| Quote: | I know that the correct is when I write:
void g(int);
void f(void*);
............
f(g);
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No, that's not correct. There is no standard conversion from
pointer-to-function to void *. There are good reasons for this,
including the fact that code and data may be stored in separate
address spaces, particularly in micro-controllers.
| Quote: | But my compiler (Visual C++ 6 and .NET) don't mind when I use it like this:
f(void g(int a));
Is it correct by standard of C++ to write like this?
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No, it's not correct. What you've written there is a declaration
(though of an archaic and non-standard form) rather than an
expression. The parameter names g and a are ignored, the function
type given as a parameter type is "adjusted" to a pointer-to-function
type, and the return type is assumed to be int. So it is equivalent
to:
int f(void (*)(int));
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