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This chapter discusses bit-oriented operations. A bit is the smallest unit of information; normally represented by the values 1 and 0. (Other representations include on/off, true/false, and yes/no.) Bit manipulations are used to control the machine at the lowest level. They allow the programmer to get "under the hood" of the machine. Many higher-level programs will never need bit operations. Low-level coding such as writing device drivers or pixel-level graphic programming requires bit operations. Eight bits together form a byte, represented by the C++ data type char . A byte might contain the following bits: 01100100 . The binary number 01100100 can also be written as the hexadecimal number 0x64. (C++ uses the prefix "0x" to indicate a hexadecimal ”base 16 ”number.) Hexadecimal is convenient for representing binary data because each hexadecimal digit represents 4 binary bits. Table 11-1 gives the hexadecimal (hex) to binary conversion. Thus, the hexadecimal number 0xAF represents the binary number 10101111. Table 11-1. Hex and binary
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