Try this:
sizeof(list) / sizeof(list[0]);
Because this question is tagged C++, it is always recommended to use std::vector in C++ rather than using conventional C-style arrays.
An array-type is implicitly converted into a pointer-type when you pass it to a function. Have a look at this.
In order to correctly print the sizeof an array inside any function, pass the array by reference to that function (but you need to know the size of that array in advance).
You would do it like so for the general case
template<typename T,int N>
//template argument deduction
int size(T (&arr1)[N]) //Passing the array by reference
{
return sizeof(arr1)/sizeof(arr1[0]); //Correctly returns the size of 'list'
// or
return N; //Correctly returns the size too [cool trick ;-)]
}