Defining a function - function prototypes

type functionName( type argname [, type, ...] )
{
    // function body
}
Example:
// define a function that adds two integers, returning their sum
int add (int lhs, int rhs)
{
    return lhs + rhs;
}

In C and C++, functions do not need to be defined before use--they only need to be declared. However, eventually the function must be defined so that it can link.

If a function has been previously declared, it must be defined with the same return value and argument types (or a new overloaded function will be created), but the names of the parameters do not have to be the same.

// declare the add function
int add (int, int);

// define the add function later
int add (int lhs, int rhs)
{
    return lhs + rhs;
}


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