C data types

In the C programming language, data types are declarations for memory locations or variables that determine the characteristics of the data that may be stored and the methods (operations) of processing that are permitted involving them.

The C language provides basic arithmetic types, such as integer and real number types, and syntax to build array and compound types. Several header files in the C standard library contain definitions of support types, that have additional properties, such as providing storage with an exact size, independent of the implementation.

Basic types

The C language provides the four basic arithmetic type specifiers char, int, float and double, and the modifiers signed, unsigned, short and long. The following table lists the permissible combinations to specify a large set of storage size-specific declarations.

The actual size of integer types varies by implementation. The standard only requires size relations between the data types and minimum sizes for each data type:

Double-precision floating-point format

Double-precision floating-point format is a computer number format that occupies 8 bytes (64 bits) in computer memory and represents a wide, dynamic range of values by using a floating point.

Double-precision floating-point format usually refers to binary64, as specified by the IEEE 754 standard, not to the 64-bit decimal format decimal64.

IEEE 754 double-precision binary floating-point format: binary64

Double-precision binary floating-point is a commonly used format on PCs, due to its wider range over single-precision floating point, in spite of its performance and bandwidth cost. As with single-precision floating-point format, it lacks precision on integer numbers when compared with an integer format of the same size. It is commonly known simply as double. The IEEE 754 standard specifies a binary64 as having:

This gives 15–17 significant decimal digits precision. If a decimal string with at most 15 significant digits is converted to IEEE 754 double precision representation and then converted back to a string with the same number of significant digits, then the final string should match the original. If an IEEE 754 double precision is converted to a decimal string with at least 17 significant digits and then converted back to double, then the final number must match the original.

Double (volleyball)

A double occurs in volleyball when a player, during a match, is credited with scoring at least ten times in one (or more) of five statistical categories: Aces, Kills, Blocks, Digs, and Assists. The term was apparently derived from similar basketball jargon; the expression "triple-double" was coined by former Los Angeles Lakers public relations director Bruce Jolesch in order to showcase Magic Johnson's versatility.

There are four main types of doubles:

Of the five statistical categories, double digit match totals are most common for assists, but rare for any positions other than setter. The next most frequent double-digit category is digs, which is most often attained by liberos or defensive specialists, but can be achieved by any strong defensive player. Kills are the third most common double-digit achievement category, occurring predominantly among hitters, especially outside hitters and middle blockers. Likewise, double-digit blocking numbers are preponderantly accomplished by middle blockers or outside hitters, but are much less common than double-digit kills. Rarest by far are double-digit aces, which even the most exceptional server is unlikely to attain once in a career.

Floor

A floor is the walking surface of a room or vehicle. Floors vary from simple dirt in a cave to many-layered surfaces modern technology. Floors may be stone, wood, bamboo, metal, or any other material that can support the expected load.

The levels of a building are often referred to as floors although a more proper term is story or storey.

Floors typically consist of a subfloor for support and a floor covering used to give a good walking surface. In modern buildings the subfloor often has electrical wiring, plumbing, and other services built in. As floors must meet many needs, some essential to safety, floors are built to strict building codes in the first world.

Special floor structures

Where a special floor structure like a floating floor is laid upon another floor then both may be referred to as subfloors.

Special floor structures are used for a number of purposes:

Valley

A valley is a low area between hills, often with a river running through it.

In geology, a valley or dale is a depression that is longer than it is wide. The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys. Most valleys belong to one of these two main types or a mixture of them, (at least) with respect to the cross section of the slopes or hillsides.

Valley terminology

A valley in its broadest geographic sense is also known as a dale. A valley through which a river runs may also be referred to as a vale. A small, secluded, and often wooded valley is known as a dell or in Scotland as a glen. A wide, flat valley through which a river runs is known in Scotland as a strath. A mountain cove is a small valley, closed at one or both ends, in the central or southern Appalachian Mountains which sometimes results from the erosion of a geologic window. A small valley surrounded by mountains or ridges is sometimes known as a hollow. A deep, narrow valley is known as a cwm (also spelled combe or coombe). Similar geological structures, such as canyons, ravines, gorges, gullies, and kloofs, are not usually referred to as valleys. See also: "chine". A valley formed by erosion is called an erosional valley; a valley formed by geologic events such as drop faults or the rise of highlands is called a structural valley.

Floor and ceiling functions

In mathematics and computer science, the floor and ceiling functions map a real number to the largest previous or the smallest following integer, respectively. More precisely, floor(x) = is the largest integer not greater than x and ceiling(x) = is the smallest integer not less than x.

Notation

Carl Friedrich Gauss introduced the square bracket notation for the floor function in his third proof of quadratic reciprocity (1808). This remained the standard in mathematics until Kenneth E. Iverson introduced the names "floor" and "ceiling" and the corresponding notations and in his 1962 book A Programming Language. Both notations are now used in mathematics; this article follows Iverson.

The floor function is also called the greatest integer or entier (French for "integer") function, and its value at x is called the integral part or integer part of x; for negative values of x the latter terms are sometimes instead taken to be the value of the ceiling function, i.e., the value of x rounded to an integer towards 0. The language APL uses ⌊x; other computer languages commonly use notations like entier(x) (ALGOL), INT(x) (BASIC), or floor(x)(C, C++, R, and Python). In mathematics, it can also be written with boldface or double brackets .