Ivor Horton's Beginning Visual C++ 2012

INITIALIZING FUNCTION PARAMETERS

With all the functions you have used up to now, you have had to take care to provide an argument corresponding to each parameter in a function call. It can be quite handy to be able to omit one or more arguments in a function call and have some default values supplied automatically for the arguments that you leave out. You can arrange this by providing initial values for the parameters to a function in its prototype.

Suppose that you write a function to display a message, where the message is passed as the argument. Here is the definition of such a function:

void showit(const char message[])
{
  cout << endl
       << message;
  return;
}

You can specify a default value for the parameter to this function by specifying the initializing string in the function prototype, as follows:

void showit(const char message[] = "Something is wrong.");

The default value for the message parameter is the string literal shown. If you omit the argument when you call the function, the default value is used.

TRY IT OUT: Omitting Function Arguments

Leaving out the function argument when you call the function executes it with the default value. If you supply the argument, it replaces the default value. You can use the showit() function to output a variety of messages.

// Ex6_03.cpp // Omitting function arguments #include <iostream> using std::cout; using std::endl; void showit(const char message[] = "Something is wrong."); int main(void) { const char mymess[] = "The end of ...