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What is a function declaration? Many novices are not very clear about this. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can gain something.

"function definition" refers to the establishment of the function, including the specified function name, function value type, formal parameter type, function body and so on. It is a complete and independent function unit. The function of "function declaration" is to inform the compiling system of the name, function type and parameter type, number and order of the function, so that the system can check it when calling the function (for example, whether the function name is correct, whether the type and number of actual participating parameters are the same).

In writing form, the function declaration can copy the function header, followed by a semicolon; and you can write only the type name of each parameter in the parameter table, but not the parameter name.

Definition of function

The definition of a function is a complete function unit:

Including function type, function name, formal parameter and formal parameter type, function body, etc.

In a program, a function can only be defined once.

There is no semicolon between the beginning of the function and the curly braces.

Declaration of function

The function declaration is just a description of the compilation system:

A function declaration is a type description of the return value of a defined function to inform the system what type of function is called in this function.

Does not contain function body (or parameter)

The function should be declared in each tone function after calling this function several times.

A function declaration is a statement that must end with a semicolon!

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