Sams Teach Yourself C in 21 Days

value of 65.11. When the program runs, it prints the correct number for each. The values

inxandyare passed into the argument kofhalf_of(). This is like copying the values

fromxtok, and then from ytok.half_of()then returns this value after dividing it by 2

(line 27).

108 Day 5

FIGURE5.4

Each time a function is

called, the arguments

are passed to the func-

tion’s parameters.

First function call z=half_of(x);

float half_of(float k)

float half_of(float k)

Second function call z=half_of(y);

3.5

65.11

The Function Body ........................................................................................

Thefunction bodyis enclosed in braces, and it immediately follows the function header.

It’s in the function body that the real work is done. When a function is called, execution

begins at the start of the body and terminates (returns to the calling program) when a

returnstatement is encountered or when execution reaches the closing brace.

Local Variables

You can declare variables within the body of a function. Variables declared in a

function are called local variables. The term localmeans that the variables are

private to that particular function and are distinct from other variables of the same name

declared elsewhere in the program. This will be explained shortly; for now, you should

learn how to declare local variables.

A local variable is declared like any other variable, using the same variable types and

rules for names that you learned on Day 3. Local variables can also be initialized when

DOuse a function name that describes

the purpose of the function.

DOmake sure that the data type of the

arguments you pass to a function match

the data types of the parameters of the

function.

DON’Tpass values to a function that it

doesn’t need.

DON’Ttry to pass fewer (or more) argu-

ments to a function than there are para-

meters. In C programs, the number of

arguments passed much match the num-

ber of parameters.

DO DON’T

NEWTERM

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