C++ Primer Plus, Fourth Edition

Binary Numbers

Whether you use decimal, octal, or hexadecimal notation for writing an integer, the computer stores it as a binary, or base 2, value. Binary notation uses just two digits, 0 and 1. As an example, 10011011 is a binary number. Note, however, that C++ doesn't provide for writing a number in binary notation. Binary numbers are based on powers of 2:

10011011	= 1×2[7] + 0×2[6] + 0×2[5] + 1×2[4] + 1×2[3]
	+ 0×2[2] + 1×2[1] + 1×2[0]
	= 128 + 0 + 0 + 16 + 8 + 0 + 2 + 1
	= 155

Binary notation makes a nice match to computer memory, in which each individual unit, called a bit, can be set to off or on. Just identify the off setting with 0 and the on setting with 1. Memory commonly is organized in units called bytes, with each byte being 8 ...