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In computer programming, an anonymous function (function literal, expression or block) is a function definition that is not bound to an identifier. Anonymous functions are often arguments being passed to higher-order functions or used for constructing the result of a higher-order function that needs to return a function. [ 1 ]
The term closure is often used as a synonym for anonymous function, though strictly, an anonymous function is a function literal without a name, while a closure is an instance of a function, a value, whose non-local variables have been bound either to values or to storage locations (depending on the language; see the lexical environment section below).
In C and C++, return exp; (where exp is an expression) is a statement that tells a function to return execution of the program to the calling function, and report the value of exp. If a function has the return type void , the return statement can be used without a value, in which case the program just breaks out of the current function and ...
Functions: Function return values can be ignored, when not needed. Function and data pointers permit ad hoc run-time polymorphism. Functions may not be defined within the lexical scope of other functions. Variables may be defined within a function, with scope. A function may call itself, so recursion is supported.
That way, a nested call can modify its local variables without affecting any of the suspended calls variables. Recursion allows direct implementation of functionality defined by mathematical induction and recursive divide and conquer algorithms. Here is an example of a recursive function in C/C++ to find Fibonacci numbers:
Forward declaration is used in languages that require declaration before use; it is necessary for mutual recursion in such languages, as it is impossible to define such functions (or data structures) without a forward reference in one definition: one of the functions (respectively, data structures) must be declared first. It is also useful to ...
In the special case of a function with a single output or input/output parameter and no return value, function composition is possible if the output or input/output parameter (or in C/C++, its address) is also returned by the function, in which case the above becomes:
The third option is safe if the closure is returned and does not require a copy but cannot be used to modify the original variable either. Java Java 8 closures can only capture final or "effectively final" non-local variables. Java's function types are represented as Classes. Anonymous functions take the type inferred from the context.