déclares

Declares, in the context of programming languages, refers to the act of introducing an identifier, such as a variable, function, or type, to the compiler or interpreter. This declaration informs the system about the existence of the identifier, its name, and often its associated type or properties. Without a declaration, a compiler might not know how to interpret or use an identifier, leading to an error.

Declarations establish the name and characteristics of an entity, but they may or may not involve the allocation of memory or the definition of its behavior. For instance, a variable declaration typically reserves memory space for it, while a function declaration might only specify its name, return type, and parameters, without providing the actual code for the function's execution.

In many languages, declarations are necessary before an identifier can be used. This ensures that the language processor has sufficient information to perform type checking, memory allocation, and other crucial operations. The exact syntax and requirements for declarations vary significantly between different programming languages. Some languages require explicit declarations for all identifiers, while others allow for implicit declarations based on usage.

The distinction between a declaration and a definition is important. A declaration introduces an identifier, while a definition provides its full implementation or initialization. For example, in C++, declaring a function specifies its signature, while defining it provides the code within the function's body. Similarly, declaring a variable might introduce its type, while defining it assigns it an initial value.