parameter
variable 
reference
parameter 
constant
reference parameter 
new variable,
copying 
reference to an
existing variable 
constant
reference to a value 
input parameter 
may be input and
should be output
parameter 
input parameter 
can modify the
parameter (bad style) 
should modify the parameter  cannot modify the parameter 
can be bound to
any expression 
must be bound to
the variable 
can be bound to any expression 
double future_value(double initial_balance, double p, int n)
{ double r = initial_balance * pow(1 + p / 100, n);
return r;
}
int main()
{ cout << "Please enter the interest rate in percent: ";
double r;
cin >> r;
double balance = future_value(10000, r, 10);
cout << "After 10 years the balance is" << balance
<< "\n";
return 0;
}
/**
Turns a number into its English name.
@param n a positive integer < 1,000,000 (e.g. 274)
@return the name of n (e.g. "two hundred seventy four")
*/
string int_name(int n);
/**
Turns a digit into its English name
@param n an integer between 1 and 9
@return the name of n ("one" ... "nine")
*/
string digit_name(int n);
/**
Turns a number between 10 and 19 into its English name.
@param n an integer between 10 and 19
@return the name of n ("ten"..."nineteen")
*/
string teen_name(int n);
/**
Gives the English name of a multiple of 10
@param n an integer between 2 and 9
@return the name of 10 * n ("twenty"..."ninety")
*/
string tens_name(int n);
string int_name(int n)
{ int c = n; /* the part that needs to be converted */
string r; /* the return value */
if (c >= 1000)
{ r = name of thousands in c + "thousand"
remove thousands from c
}
if (c >= 100)
{ r = r + name of hundreds in c + "hundreds"
remove hundreds from c
}
if (c >= 20)
{ r = r + name of tens in c
remove tens from c
}
if (c >= 10)
{ r = r + name of c
c = 0
}
if (c > 0)
r = r + name of c;
return r;
}
if (c >= 1000)
{ r = int_name(c / 1000) + " thousand";
c = c % 1000;
}
int_name(416) c r 416 ""
int_name(416) c r 416 ""
digit_name(4) Returns "four"
int_name(416) c r416"" 16 "four hundred"
int_name(416) c r416""16"four hundred" 0 "four hundred sixteen"
Syntax 5.6 : Assertions assert(expression);

double future_value(double initial_balance, double p, int n)
{ assert(p >= 0);
assert(n >= 0);
return initial_balance * pow(1 + p / 100, n);
}
/**
Computes the value of an investment with compound interest.
@param initial_balance the initial value of the investment
@param p the interest rate in percent; must be >= 0
@param n the number of periods the investment is held; must be >= 0
@return the balance after n periods
*/