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Putting array into functions

Started by asdasd12345 Jan 24, 2004 at 4:51 PM 2 replies 300+ views

Original Post

Jan 24, 2004 at 4:51 PM

I have a function that takes an array of integers, what I want to know is why you have to define an another array of integers before making the function call. for example : int Function(int Num[16]) { } int main() { int arr[]={0,1,0,2,0,3,0,4}; Function(arr); return 0; } why cant I just write, Function({0,1,0,2,0,3,0,4}); I dont know much about this stuff but when I make the in arr[] array arent I using up extra memory than I would be if I just wrote Function({0,1,0,2,0,3,0,4}). It seems a bit inefficient. I have read something about operator overloading, but Im sketchy on it, so could you overload operators to make it so you can write Function({0,1,0,2,0,3,0,4}) and have it compile, because Ive tried that and it doesnt work.

Nervo

101

Nervo

Jan 24, 2004 at 5:09 PM

this is what I did with your code:


void Function(int* Num)
{
	*Num = 99;
}

int main()
{
int arr[]={0,1,0,2,0,3,0,4};
Function(arr);
cout << *arr;
getchar();
return 0;
}

when ''arr'' is passed into the function, the address is passed for the first element. So when you work with it you''re not making a second array..you are referencing the original one through a pointer. In the example above I pass the array with a pointer and make a change to the first element then exit off the function. In main I output ''arr'' and as expected its 99, which is proof that only one array is used, so no excessive memory overhead.

asdasd12345

Author

asdasd12345

Jan 24, 2004 at 5:15 PM

Thanks, i see what your saying, I guess what annoys me is that you cant just say Function({0,1,0,2,0,3,0,4}); - just seems a bit weird to me, maybe theres a good reason for it and i just dont know what it is.

SiCrane

Mod

473

SiCrane

Jan 24, 2004 at 5:31 PM

The problem with using an aggregate initializer list like that is that the aggregate is untyped. You need at least some sort of type specifier in order to disambiguate the expression. In C++ there''s no way to declare the type of the aggregate without binding it to a variable.
However, with the 1999 revision of the C standard you can do something like:


void Function(int * p) {}

int main() {
  Function((int [8]){0, 1, 0, 2, 0, 3, 0, 4});
  return 0;
}

and have things compile.

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