Function pointer, how to cast?

Question

I wrote a function to test functions. I want to be flexible, that's the reason for the function pointer.

My code is working, but is there a possibility to avoid the warning below? I thought about a cast.

So I tried to set a (UINT32 *) in front of the &tickGet, but it isn't working.

Can you help me?

ULONG tickGet (void);

void WCET_Measurement(UINT32 (*Function)(void)){}

WCET_Measurement(&tickGet);

Compiler Warning

warning: passing arg 1 of `WCET_Measurement' from incompatible pointer type

why use both ULONG and UINT32? have you tried using one of those? — Dariusz
– Dariusz, Commented Jan 16, 2013 at 14:21

Oliver Charlesworth · Accepted Answer · 2013-01-16 14:21:41Z

3

Casting function pointers is well-defined. However, invoking a function through an incompatible pointer is undefined behaviour. So if UINT32 is a distinct type from a ULONG, then things will be wrong.

But if you really want to cast, then you can do this:

WCET_Measurement((UINT32 (*)(void))&tickGet);

Or better yet, use a typedef:

typedef UINT32 (*MyFunc)(void);

WCET_Measurement((MyFunc)&tickGet);

answered Jan 16, 2013 at 14:21

Oliver Charlesworth

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2 Comments

Oliver Charlesworth Over a year ago

@user1829804: Are you sure you copied my example precisely?

user1829804 Over a year ago

SORRY, don'T know what but It was my fault

unwind · Accepted Answer · 2013-01-16 14:22:18Z

1

Your cast attempt was wrong.

You need:

WCET_Measurement(((UINT32)(*)(void)) tickGet);

It's often good to use a typedef with function pointers, to make them clearer.

Of course, if the two types UINT32 and ULONG are different on your system, this will break horribly.

answered Jan 16, 2013 at 14:22

unwind

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1 Comment

user1829804 Over a year ago

SORRY, don'T know what but It was my fault

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