I don't know how else to explain, but this certainly was picked up by the original poster since he asked me the next question on that, which told us he wanted to convert the bytes to integer manually. My response to this post "then you need to write your own binary to decimal function" explains the next step without going into unecesary details, which as I mentioned should be left to the OP to be figured out.
Ah, you mean convert each individual byte into an unsigned int. If that's really what the poster meant, then sorry -- I misinterpreted. But I think the poster means that they want to amalgamate the four bytes and get a single, four-byte integer value.
By the way, for converting a byte to an int, just ANDing with 0xff is common and efficient.
On pondering over it now, I feel, even I might have misinterpreted, cause this 4 bytes thing didn't cross my mind, I was of the notion that he wanted the integer value of each of them. Well, nevermind, the OP has both the solutions, he can choose the appropriate one. Cheers !!