c++ - Drawing up a hexadecimal number from several decimal numbers

Question

I have a vector container. There are a number from 0 to 255. The data bytes are top (of the container). On the fourth day begins mantissa and it may consist of several numbers, for example. Mantissa consists of <120, 111, 200>. That is, it is the number of machine: <0x78, 0x6F, 0xC8>. Total turn mantissa: 0x786FC8.

I can convert because of the method:

1. Set the number of 120, 111, 200 in hexadecimal.(0x78, 0x6F, 0xC8)
2. Put the numbers in line.("78" "6F" "C8")
3. Fold the line.("786FC8")
4. Move back to an integer type. 0x786FC8

Q: Is there any way you do it faster and without strings?

Answer 1

It sounds like you want <120, 111, 200> → (120 * 256 + 111) * 256 + 200.