1. More on Functions
ANSI-C

2. Function Type and Value
A function can return a value.
Like all values in C, a function return value has a type.
The function is said to have the type of its returned value.
/* computes net price of a retail item */
double net ( double gross, int disc, int taxPer){
double discounted = gross – gross*disc/100.0;
double tax = discounted*taxPer/100.0;
return discounted + tax; }
Examples of call:
double finalPrice = net( 5.15, 10, 8);

3. Attributes of a variable
name
Type
Value
Location in memory
Arguments and parameters must match in:
Number
Order

4. Function examples And the call:
/* computes net price of a retail item */
double net ( double gross, int disc, int taxPer){
double discounted = gross – gross*disc/100.0;
double tax = discounted*taxPer/100.0;
return discounted + tax; }
And the call:
double finalPrice = net( 5.15, 10, 8);
Argument values are used to initialize the parameters
More specifically: For each parameter
Corresponding argument is evaluated
A copy of resulting value is given as value to the parameter
After parameter initialization, no more communication between argument and parameter exists.
This is called: pass-by-value

5. Assume the main declares
/* computes net price of a retail item */
double net ( double gross, int disc, int taxPer){
double discounted = gross – gross*disc/100.0;
double tax = discounted*taxPer/100.0;
taxPer = 0.0;
gross = 0.0;
return discounted + tax; }
Assume the main declares
double gross = 100.0;
int discount = 20;
int taxRate = 8.6;
double total = net(gross, discount, taxRate);
printf(“ gross>>%f , tax Rate>>%d”, gross, taxRate);
It will print:
gross>>100.0, tax Rate>>8.6 /* No CHANGE */

6. Functions which do not return values
The keyword void has two different rolls in this function definition.
/* write separator line on output*/
void PrintBannerLines (void) {
printf(“***************\n”); }
indicates that the function does not return an output value.
indicates that the function expects no parameters.

7. More examples void displayNet( double net){
printf(“The net price of the item is $%7.2f”, net); }
void displayNet( double gross, int discRate, int taxRate, double net){
printf(“Item princing information\n”);
printf(“ gross price>>$%7.2f\n”, gross);
printf(“ discount rate>>$%d\n”, discRate);
printf(“ tax rate>>$%d\n”, taxRate);
printf(“ net price>>$%7.2f\n\n”, net);