Data

Computers can only perform arithmetic and logic operations in the field $\mathbb{F}_2=\{0,1\}$ . A set of 8 bits is called a byte. The 8086 and 80286 had a 16-bit bus (the bus is the data transfer capacity per clock tick); modern Intel-based processors have 32- or 64-bit wide buses. An $n$ -bit wide memory chunk can hold $2^n$ different values. These are either indexed from $-2^{n-1}$ to $2^{n-1}-1$ or from 0 to $2^n-1$ . An integer in C/C++ on an Intel architecture is usually stored in 32 bits (=4 bytes). Floating point values are stored (usually in 8 bytes) according to a specific code. Any type of data that can be represented by an encoding of finite-sized integers can be stored in a computer memory. In C/C++ data are categorized according to their types. Data types can be elementary: bool (C++ only), char, short, int, long, float, double or user-defined: union, struct, class (C++ only). A user-defined data type is a finite sequence of existing data types and occupies either the sum (struct, class) or the maximum (union) of the sizes of the sequence elements. Memory addresses, by contrast, normally occupy a fixed amount of storage (32 bits in 32-bit CPUs).