HP Prime Graphing Wireless Calculator Instrukcja Użytkownika Pobierz pdf (Strona 617)

100

101

Functions, their arguments, and parameters

You can dene your own functions in a program, and data can be passed to a function using parameters.

Functions can return a value (using the RETURN statement) or not. When a program is executed from Home

view, the program will return the value returned by the last statement that was executed.

Furthermore, functions can be dened in a program and exported for use by other programs, in much the

same way that variables can be dened and used elsewhere.

In this section, we will create a small set of programs, each illustrating some aspect of programming in the HP

Prime. Each program will be used as a building block for a custom app.

Program ROLLDIE

We’ll rst create a program called ROLLDIE. It simulates the rolling of a single die, returning a random integer

between 1 and whatever number is passed into the function.

In the Program Catalog create a new program named ROLLDIE. (For help, see Creating a new program

on page 554.) Then enter the code in the Program Editor.

EXPORT ROLLDIE(N)

BEGIN

RETURN 1+RANDINT(N-1);

END;

The rst line is the heading of the function. Execution of the RETURN statement causes a random integer

from 1 to N to be calculated and returned as the result of the function. Note that the RETURN command

causes the execution of the function to terminate. Thus any statements between the RETURN statement and

END are ignored.

In Home view (in fact, anywhere in the calculator where a number can be used), you can enter ROLLDIE(6)

and a random integer between 1 and 6 inclusive will be returned.

Program ROLLMANY

Because of the EXPORT command in ROLLDIE, another program could use the ROLLDIE function and generate

n rolls of a die with any number of sides. In the following program, the ROLLDIE function is used to generate

n rolls of two dice, each with the number of sides given by the local variable sides. The results are stored in

list L2, so that L2(1) shows the number of times the dies came up with a combined total of 1, L2(2) shows the

number of times the dies came up with a combined total of 2, etc. L2(1) should be 0 (since the sum of the

numbers on 2 dice must be at least 2).

Here we use the Store operator (▶) in place of :=. Press to retrieve this operator. The syntax

is Var ▶ Value; that is, the value on the right is stored in the variable on the left.

EXPORT ROLLMANY(n,sides)

BEGIN

LOCAL k,roll;

// initialize list of frequencies

MAKELIST(0,X,1,2*sides,1) ▶ L2;

The HP Prime programming language 569

1 2 ... 612 613 614 615 616 617 618 619 620 621 622 ... 700 701

Komentarze do niniejszej Instrukcji

Brak uwag

HP Prime Graphing Wireless Calculator Instrukcja Użytkownika Strona 617

Komentarze do niniejszej Instrukcji

Powiązane produkty i podręczniki dla Oprogramowanie HP Prime Graphing Wireless Calculator