MODUL IV
STRUKTUR KENDALI
PERCABANGAN BERSYARAT DENGAN
IF ... THEN DAN IF ... THEN ... ELSE ...
A. TUJUAN
- Memahami
salah satu jenis statement kendali untuk pemilihan proses
- Memahami
proses pengambilan keputusan dengan statement if ... then ... else ...
- Memahami
variasi proses pengambilan keputusan dalam bentuk tunggal
- Mampu
mengaplikasikan proses pengambilan keputusan dalam program
B. DASAR TEORI
Sebuah program sering kali
harus dapat memilih pernyataan mana yang akan dikerjakan berdasarkan suatu
kondisi logika tertentu, misalnya bagaimana membuat program untuk mengetahui
bilangan mana yang lebih besar di antara 2 (dua) buah bilangan.
Untuk menyelesaikan
persoalan di atas, Pascal menyediakan fasilitas pengambilan keputusan, yaitu
dengan statement IF ... THEN ... ELSE ...
Bentuk umum untuk IF ... THEN ...
IF
(ekspresi logika) THEN
BEGIN
bagian yang dikerjakan
jika ekspresi logika bernilai benar (TRUE)
END;
Bentuk umum untuk IF ... THEN ... ELSE ...
IF
(ekspresi logika) THEN
BEGIN
bagian yang dikerjakan
jika ekspresi logika bernilai benar (TRUE)
END
{tanpa titik koma}
ELSE
BEGIN
bagian yang dikerjakan
jika ekspresi logika bernilai salah
(FALSE)
END;
C. LATIHAN SOAL
- Nomor Program 0401
a. Tulislah program berikut ini, kemudian
amati outputnya!
PROGRAM tanya;
USES CRT;
VAR a : real;
BEGIN
CLRSCR;
WRITE(‘Masukkan sebuah bilangan
di bawah 100! ’);
READLN(a);
IF a<100 THEN
WRITE(‘Terima Kasih’);
READLN;
END.
b. Apa yang terjadi jika anda memasukkan
nilai kurang dari 100, jelaskan!
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c. Apa yang terjadi jika anda memasukkan
nilai lebih dari 100, jelaskan!
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- Nomor Program 0402
a. Tulislah program berikut ini, kemudian
amati outputnya!
PROGRAM nilai_maksimal;
USES CRT;
VAR a, b, max : integer;
BEGIN
CLRSCR;
TEXTCOLOR(lightblue);
WRITE(‘Masukkan bilangan
pertama : ’);READLN(a);
WRITE(‘Masukkan bilangan
kedua : ‘);READLN(b);
IF a>b THEN
max:=a
ELSE
max:=b;
WRITELN(‘Bilangan terbesar
adalah ‘,max);
READLN;
END.
b. Modifikasilah program di atas sehingga
output yang ditampilkan adalah nilai terbesar adalah bilangan pertama (jika
bilangan pertama memiliki nilai terbesar) atau nilai terbesar adalah bilangan
kedua (jika bilangan kedua memiliki nilai terbesar)!
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c. Gantilah bagian-bagian tertentu dari
program di atas sehingga dapat digunakan untuk menampilkan bilangan yang
memiliki nilai terkecil!
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- Nomor Program 0403
a. Tulislah program berikut ini, kemudian
amati outputnya!
PROGRAM nilai_ujian;
USES CRT;
VAR nilai : real;
nil_huruf : char;
BEGIN
CLRSCR;
WRITE(‘Tulis nilai ujian anda
(0-100) : ‘);
READLN(nilai);
SOUND(1000); DELAY(1000);
NOSOUND;
IF nilai>=80 THEN
nil_huruf:=’A’
ELSE IF nilai>=70 THEN
nil_huruf:=’B’
ELSE IF nilai>=60 THEN
nil_huruf:=’C’
ELSE IF nilai>=20 THEN
nil_huruf:=’D’
ELSE
nil_huruf:=’E’;
WRITELN(‘Nilai Anda :
‘,nil_huruf);
READLN;
END.
b. Modifikasilah program di atas sehingga
apabila user memasukkan angka di atas 100, maka program akan memberi pesan
kesalahan!
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- Nomor Program 0404
Buatlah program yang akan menampilkan pesan apakah
bilangan (0-65535) yang user masukkan adalah bilangan genap atau ganjil!
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- Nomor Program 0405
Seorang karyawan bekerja di perusahaan X. Karyawan
tersebut digaji dengan mengikuti ketentuan PTKP (Penghasilan Tidak Kena Pajak)
dan PKP (Penghasilan Kena Pajak). PTKP berlaku bagi karyawan yang digaji di
bawah 360000 per bulan, sedangkan bagi karyawan yang gajinya adalah 360000 ke
atas akan tergolong PKP, dengan pajak 10% dari Penghasilan Kena Pajak (PKP).
PKP = (Gaji-360000). Misalnya seorang karyawan digaji sebesar 500000, maka PKP
= 500000 – 360000 = 140000. Jadi, pajak yang harus dibayar = 140000 x 10% =
14000.
Berdasarkan kasus di atas, buatlah program untuk
menentukan pajak yang harus dibayar oleh karyawan, yang mana ketika program
dijalankan, program akan meminta masukan dari user berupa penghasilan perbulan.
Berikut ini contoh output program :
dan
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