Temporary variable

In computer programming, a temporary variable is a variable whose purpose is short-lived, usually to hold temporarily data that will soon be discarded, or before it can be placed at a more permanent memory location. Because it is short-lived, it is usually declared with local scope. There is no formal definition of what makes a variable "temporary", but it is an often–used term in programming.

A typical example would be that of swapping the contents of two variables. To swap the contents of variables "a" and "b" one would typically use a temporary variable "temp" as follows, so as to preserve the data from "a" as it is being overwritten by "b":

temp := a a := b b := temp

(See the XOR swap algorithm for swapping without a temporary variable.)A more real example is that of swapping two elements in an array, as it is done in the RC4 algorithm and in sorting algorithms.

Temporary variables are usually named with identifiers that abbreviate the word "temporary", such as "temp", "tmp" or simply "t", orwith common metasyntactic variable names, the most common of which are "foo", "bar", "baz" (See also foobar).

ee also

*Temporary folder
*Temporary file
*Temporary filesystem