Our third style of function takes no arguments, but
will
return a value. Up until now, we have been communicating information TO
a called function. Now we will be returning information FROM the
function by using the function return value.
The return value can be a constant, a variable, or an expression.
The only requirement is that the return value be of the type specified
in the function prototype.
return_type
functionName(void)
//function header
{
statements;
return (value);
//value is of type return_type
}
Function calls that
return values need to have a place in main for the returned value to reside,
to be printed, or to be manipulated. Think of the
function as holding out its hand to pass a value back to main. Main
must stretch out its hand (which may be a variable location) for this value
to reside.
Always
be sure to do something with a returned
value! Store the return value somewhere; print the return value to the
screen; use the return value in a calculation; just use it!! The following are examples of
USES of function return values:
(Function calls with return locations)
x = Avg( i, j)
(Function Avg takes i and j and returns
a value stored in x.)
cout<< num(1,3,5); (Function num
takes 1, 3 and 5 and its return value is printed)
ans=add(a,b) + add(c,d);
(Function add is called twice. The return values from 2 calls
are added and stored in ans.)
//Example program
//Screen display shown at the right
//Returning values from a function
#include<iostream.h>
#include<stdlib.h>
void greeting(int x);
//prototype-no
return
int getNumber(void);
//prototype-return integer
int main(void)
{
system("CLS");
greeting(5); //function
call
int response;
response=getNumber( ); //call
and store value
greeting(response); //function
call
return 0;
}
//function definition -
creates a line of "Hi"s
void greeting(int x)
{
int i;
for(i = 0; i < x; i++)
{
cout<<"Hi
";
}
cout<<endl;
return;
}
//function definition -
get the user's # and return it
int getNumber(void)
{
int number;
do
{
cout<<"Please
enter number (1-10)\n";
cin>>number;
}
while((number < 1)||(number > 10));
return (number);
}
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