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define functions in c++. what are various functions in c++?
The general form of a C++ function definition is as follows:

return_type function_name( parameter list )
{
   body of the function
}

A C++ function definition consists of a function header and a function body. Here are all the parts of a function:

Return Type: A function may return a value. The return_type is the data type of the value the function returns. Some functions perform the desired operations without returning a value. In this case, the return_type is the keyword void.

Function Name: This is the actual name of the function. The function name and the parameter list together constitute the function signature.

Parameters: A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. Parameters are optional; that is, a function may contain no parameters.

Function Body: The function body contains a collection of statements that define what the function does.


A function declaration tells the compiler about a function name and how to call the function. The actual body of the function can be defined separately.

A function declaration has the following parts:

return_type function_name( parameter list );
For the above defined function max(), following is the function declaration:

int max(int num1, int num2);
Parameter names are not importan in function declaration only their type is required, so following is also valid declaration:

int max(int, int);
Function declaration is required when you define a function in one source file and you call that function in another file. In such case you should declare the function at the top of the file calling the function.


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