Sizeof in function

Question

How do I get the size of bits of an Array from a function

int NumberOfElements(int Array[]);

int main()
{
    int Array[] = { 5,5,6,5,5 };
    std::cout << NumberOfElements(Array);
}
int NumberOfElements(int Array[]) {
    return sizeof(Array);
}

It's returning 4. Result should be 20.

https://en.cppreference.com/w/cpp/iterator/size – Jesper Juhl Feb 07 '20 at 20:10 — Jesper Juhl, Feb 07 '20 at 20:10

score 5 · Answer 1 · answered Feb 07 '20 at 20:03

5

Arrays decay into pointers when passed as arguments to functions etc. The size 4 means that the pointer has that size. It does not tell you anything about the number of elements in the actual array.

You may want to use a std::vector<int> instead where the size is part of its interface:

#include <vector>

int main()
{
    std::vector<int> Array{ 5,5,6,5,5 };
    std::cout << NumberOfElements(Array);
}
int NumberOfElements(const std::vector<int>& Array) {
    return Array.size();
}

answered Feb 07 '20 at 20:03

Ted Lyngmo

93,841
5
60
108

I thought 4 for the int type. Thanks for the clarification. – User_67128 Feb 07 '20 at 20:05
@ManojBanik It may be, but you are probably on a 32 bit machine and `int` and pointers may have the same size. – Ted Lyngmo Feb 07 '20 at 20:06

Sizeof in function

1 Answers1

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