Question

I’ve the following C++ array:

byte data[] = {0xc7, 0x05, 0x04, 0x11 ,0x45, 0x00, 0x00, 0x00, 0x00, 0x00};

How can I know how many items there are in this array?

Answer 1

For byte-sized elements, you can use sizeof(data).

More generally, sizeof(data)/sizeof(data[0]) will give the number of elements.

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Since this issue came up in your last question, I’ll clarify that this can’t be used when you pass an array to a function as a parameter:

void f(byte arr[])
{
    //This always prints the size of a pointer, regardless of number of elements.
    cout << sizeof(arr);
}

void g()
{
    byte data[] = {0xc7, 0x05, 0x04, 0x11 ,0x45, 0x00, 0x00, 0x00, 0x00, 0x00};
    cout << sizeof(data);    //prints 10
}