An unreferenced variable in the

source code In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the wo ...

of a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer program ...

is a

variable Variable may refer to: * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed * Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many ...

that is defined but which is never used. This may result in a harmless waste of memory. Many

compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that ...

s detect such variables and do not allocate storage for them (i.e., "optimize away" their storage), generally also issuing a warning as they do. Some coding guideline documents consider an unreferenced variable to be a symptom of a potential coding fault. On the other hand, unreferenced variables can be used as temporary placeholders to indicate further expected future developments in the code.

Examples

C: int main(void) In this example, j is an unreferenced variable.

References

Variable (computer science) {{Compu-prog-stub