In computer science, primitive data types are a set of basic data types from which all other data types are constructed. Specifically it often refers to the limited set of data representations in use by a particular processor, which all compiled programs must use. Most processors support a similar set of primitive data types, although the specific representations vary. More generally, "primitive data types" may refer to the standard data types built into a programming language (built-in types). Data types which are not primitive are referred to as derived or composite.
Primitive types are almost always value types, but composite types may also be value types.
Common primitive data types
The most common primitive types are those used and supported by computer hardware, such as integers of various sizes, floating-point numbers, and Boolean logical values. Operations on such types are usually quite efficient. Primitive data types which are native to the processor have a one-to-one correspondence with objects in the computer's memory, and operations on these types are often the fastest possible in most cases. Integer addition, for example, can be performed as a single machine instruction, and some offer specific instructions to process sequences of characters with a single instruction. But the choice of primitive data type may affect performance, for example it is faster using SIMD operations and data types to operate on an array of floats.
Integer numbers
An integer data type represents some range of mathematical integers. Integers may be either signed (allowing negative values) or unsigned (non-negative integers only). Common ranges are:
Floating-point numbers
A floating-point number represents a limited-precision rational number that may have a fractional part. These numbers are stored internally in a format equivalent to scientific notation, typically in binary but sometimes in decimal. Because floating-point numbers have limited precision, only a subset of real or rational numbers are exactly representable; other numbers can be represented only approximately. Many languages have both a single precision (often called "float") and a double precision type (often called "double").
Booleans
A boolean type, typically denoted "bool" or "boolean", is typically a logical type that can have either the value "true" or the value "false". Although only one bit is necessary to accommodate the value set "true" and "false", programming languages typically implement boolean types as one or more bytes.
Many languages (e.g. Java, Pascal and Ada) implement booleans adhering to the concept of boolean as a distinct logical type. Some languages, though, may implicitly convert booleans to numeric types at times to give extended semantics to booleans and boolean expressions or to achieve backwards compatibility with earlier versions of the language. For example, early versions of the C programming language that followed ANSI C and its former standards did not have a dedicated boolean type. Instead, numeric values of zero are interpreted as "false", and any other value is interpreted as "true". The newer C99 added a distinct boolean type _Bool (the more intuitive name bool as well as the macros true and false can be included with stdbool.h), and C++ supports bool as a built-in type and "true" and "false" as reserved words.
Specific languages
Java
The Java virtual machine's set of primitive data types consists of: byte, short, int, long, char (integer types with a variety of ranges) float and double, floating-point numbers with single and double precisions boolean, a Boolean type with logical values true and false returnAddress, a value referring to an executable memory address. This is not accessible from the Java programming language and is usually left out.
C basic types
The set of basic C data types is similar to Java's. Minimally, there are four types, char, int, float, and double, but the qualifiers short, long, signed, and unsigned mean that C contains numerous target-dependent integer and floating-point primitive types. C99 extended this set by adding the boolean type _Bool and allowing the modifier long to be used twice in combination with int (e.g. long long int).