c++ sizeof(array) return twice the array's declared length

Question

I have a section of code in which two array are declared with sizes of 6 and 13, but when \'sizeof()\' is used the lengths are returned as 12 and 26.

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Answer 1

sizeof returns the size in bytes, which for an array is the number of items × the size of each item. To get the number of items divide by the size of one element.

sizeof(races) / sizeof(races[0])

Be careful with this. It will only work for arrays whose size is known at compile time. This will not work:

void func(short int array[])
{
    // DOES NOT WORK
    size_t size = sizeof(array) / sizeof(array[0]);
}

Here array is actually a short int * and sizeof(array) does not return the actual size of the array, which is unknown at compile time.

This is one of many reasons to prefer std::vector or std::array to raw arrays in C++.