Question

I am writing a program that needs to take an array of size n and convert that into it’s hex value as follows:


int a[] = { 0, 1, 1, 0 };


I would like to take each value of the array to represent it as binary and convert it to a hex value. In this case:

0x6000000000000000; // 0110...0

it also has to be packed to the right with 0’s to be 64 bits (i am on a 64 bit machine).

Or i could also take the array elements, convert to decimal and convert to hexadecimal it that’s easier… What you be the best way of doing this in C++?

(this is not homework)

Answer 1

The following assumes that your a[] will only ever use 0 and 1 to represent bits. You’ll also need to specify the array length, sizeof(a)/sizeof(int) can be used in this case, but not for heap allocated arrays. Also, result will need to be a 64bit integer type.

for (int c=0; c<array_len; c++)
  result |= a[c] << (63-c);

If you want to see what it looks like in hex, you can use (s)printf( "%I64x", result )