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In mathematics, a unary operation is an operation with only one operand, i.e. a single input. [1] This is in contrast to binary operations , which use two operands. [ 2 ] An example is any function f : A → A {\displaystyle f:A\rightarrow A} , where A is a set ; the function f {\displaystyle f} is a unary operation on A .
It also means that, for example, the bitand keyword may be used to replace not only the bitwise-and operator but also the address-of operator, and it can even be used to specify reference types (e.g., int bitand ref = n). The ISO C specification makes allowance for these keywords as preprocessor macros in the header file iso646.h.
GCC extends the C language with a unary && operator that returns the address of a label. This address can be stored in a void* variable type and may be used later in a goto instruction. For example, the following prints "hi "in an infinite loop:
As another example, the scope resolution operator :: and the element access operator . (as in Foo::Bar or a.b) operate not on values, but on names, essentially call-by-name semantics, and their value is a name. Use of l-values as operator operands is particularly notable in unary increment and decrement operators. In C, for instance, the ...
The successor function, denoted , is a unary operator.Its domain and codomain are the natural numbers; its definition is as follows: : (+) In some programming languages such as C, executing this operation is denoted by postfixing ++ to the operand, i.e. the use of n++ is equivalent to executing the assignment := ().
In programming the two's complement, address reference, and the logical NOT operators are examples of unary operators. All functions in lambda calculus and in some functional programming languages (especially those descended from ML ) are technically unary, but see n-ary below.
In languages syntactically derived from B (including C and its various derivatives), the increment operator is written as ++ and the decrement operator is written as --. Several other languages use inc(x) and dec(x) functions. The increment operator increases, and the decrement operator decreases, the value of its operand by 1.
Unary function, a function that takes one argument; in computer science, a unary operator is a subset of unary function; Unary operation, a kind of mathematical operator that has only one operand; Unary relation, a mathematical relation that has one argument; Unary coding, an entropy encoding that represents a number n with n − 1 ones ...