függvénydeklarációtól

Függvénydeklarációtól refers to the concept of defining a function before it is used in a program. This is a fundamental aspect of many programming languages, ensuring that the compiler or interpreter knows the function's signature, return type, and parameters before encountering a call to that function. In languages that require explicit declarations, a function must be declared before it can be called. This declaration provides the necessary information for the program to correctly link function calls to their definitions. Without a prior declaration, the program might not understand how to execute the function, leading to compilation or runtime errors.

The declaration typically includes the function's name, the data types of its parameters, and the data type of the value it will return. For example, in C++, a function declaration might look like int addNumbers(int a, int b);. This tells the compiler that there is a function named addNumbers that takes two integers as input and will return an integer. The actual implementation, or definition, of the function can appear later in the code. This separation of declaration and definition allows for greater flexibility in code organization, enabling functions to be defined in different files or compiled separately. The principle of "declaration before use" helps to create more robust and maintainable code.