# Expression (programming)

An expression is in many programming a construct that according to a given semantics in relation to a context analyzed can be, so a value.

In many formal languages, expressions are one of the most important constructs, if not the only one. Some examples:

Arithmetic expressions
`2*3; 2(x − a); x2 = 2x; y= sin(x);` etc.
Propositional expressions
`a und b; wenn b dann a; a oder nicht b;` etc.
Predicate logic expressions
`wenn verheiratet(A, B) dann verheiratet(B, A); wenn Mensch(A) dann (Mann(A) oder Frau(A));` etc.

Expressions in programming languages

• Literals (constants) `2`, `3.14`... (But strings (strings) and symbols: `"Hallo Welt"`, `'c'`, ...)
• Variables : `x`, `betragInEuro`, `wochentagsNummer`, ...
• Features : `sin(phi)`, `random()`, `aktMonatsNummer()`, ...
• Operations : `2*3`, `2(x - a)`, `x^3`, `cos(2*x + 3.14)`, ...
• Combined terms, some of them with assignments or expression statements : `x++`, `--y`, `y = x = 2*z`, `y = sin(x)`, ...

In addition to expressions, declarations that define the context for the expressions are important in many formal languages . These are sometimes (especially in functional programming languages and scripting languages ) themselves viewed as expressions.