Different Function Arguments

**KansaiRobot** · 04-15-2012

Hello. I would appreciate very much if anyone can help me in the following

I know you can overload a method in C++ using the same name of a function for different versions with different number of arguments

But checking the code in C that I am working with I found the following

a function defined in one file as

Code:

void SRecvEth(void)
{
// blablabla
}

then in another file I have

Code:

void SRecvEth(unsigned int SOCK_NO);

and lower in that file the function called as

Code:

SRecvEth(SOCK_NO);

I build the code without problems! How can this be possible? Shouldnt this generate an error?! am I missing something?

**oogabooga** · 04-15-2012

am I missing something?

Yep. The first file is missing the function prototype to check that it matches the function definition.
Instead of having the line

Code:

void SRecvEth(unsigned int SOCK_NO);

in the second file, that line should be in a header file and should be included in both files. By including it in the first file the definition can be checked against the declaration.

**KansaiRobot** · 04-15-2012

Thank you for the answer. And sorry for not being clear
I mean I have received code that was written by another developer and my work now is to do a version up of the code, modify it to new requirements etc.
So far I am reading the code I have been handled and found what I described above. Even though the arguments dont match, the code can be built, and that is what I dont understand. Is that legal in C? how come my compiler doesnt give me an error?

**oogabooga** · 04-15-2012

No, it is not legal in C, but the compiler doesn't emit an error because the code is not structured properly. The declaration for SRecvEth should be in a header file and should be included in both the implementation file for that function as well as all files that use the function. That way the compiler can check that calls are correct. Each file is compiled on its own and only knows the way to call a function in a another file because of the prototype. If the prototype is incorrect there's no way to determine that across files. The code generated for the second file is pushing an argument for the function to use, but the code generated for the function definition in the first file is not accepting that argument. It's basically just ignoring it. Obviously this is an error and you should fix it.

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