Type 1
There is no data communication among the calling portion of a program and a called function block. A function calling environment invokes the function through not passing any formal argument and the function does not return back any value to the caller.
Example:
# include<iostream.h>
void main( void)
{
void message ( void); // function declaration
message( ); // function calling
}
void message (void) // function definition
{
-----
-----
}