A declaration is a form of statement, which expresses (or declares) some idea; declarations attempt to argue that something is true. Some types of written text are said to be declarations, such as the US Declaration of Independence or the proposed Unilateral Declaration of Independence of Quebec.

Grammar

In the study of grammar, a declaration or declarative sentence is a sentence that is used to state a fact or argument.

Cricket

In the sport of cricket a declaration occurs when a captain declares his team's innings closed.

Computer Science

In computer science, a declaration specifies a variable's dimensions, identifier, type, and other aspects. The declaration, and any related initializer, forms the definition; usually, the declaration and definition are the same thing. Definitions reserve memory. Definitions and declarations can also be used for subroutines (functions); where, they are sometimes referred to as "prototypes". Once again, in some cases the definition and the prototype are the same thing.

Initialization allows a program to assign an initial value to a variable. Below is an example of a C++ function (also C; the syntax does not differ in this case) which declares an integer variable, x; this is followed by an example where the variable has been initialized to seven, x = 7:

void example1()
{
  int x;
}

void example2()
{
  int x = 7;
}