Page 258 - PowerPoint Presentation

CAVITE STATE UNIVERSITY
TRECE MARTIRES CITY CAMPUS
Department of Information Technology DCIT 111 - Advanced Programming

Week 5: Elements of Programming Languages Continuation
Objective: After the completion of the chapter, students will be able to:
 Learn the fundamentals of High-level programming language
 Perform different operations and instructions using High-level programming language
 Create a simple program applying conditional statements, looping and array.
 Write program codes in a piece of paper

Repetition Statements
Java provides three repetition structures: while, do-while and for. These statements
are also known as loops. We shall look into the syntaxes of these structures first and also
learn how we can formulate algorithms using these loops.

The while loops
Following is the syntax of the while loop. The statement in the while blocks are
executed as long as the condition evaluates to true.
while (condition) {
statement;
}

For this loop to end, the condition should at some point of time become false. This is
achieved using counters. Counters are simple variables which are incremented every time the
body of the loop is executed. They are used to keep track of the number of times the loop is
executed. The value of counter is used in the conditional expression to determine the end of
the loop. Consider the following code below which is used to print the statement “Hi!” five times
on the screen.
initialization; int i = 0;

while (condition) { while (i <5) {
// body System.out.println(“Hi!);
increment / decrement; i++;
} }

The value of the integer variable i is first set to zero. When control enter the while
statement, the condition i<5 is evaluated. Since 0<5 is true, the body of the loop is executed.
The statement “Hi!” is printed and i is incremented to 1. The condition is evaluated again, i<5
or 1<5 is still true. The body of the loop is again executed. In this way, the while loop executes
five times after which i becomes 5. Now, since the condition is 5<5 evaluates to false, control
moves out of the while loop. In the above program, we can eliminate the i++; statement and
include it in the while condition itself by using increment operator.
While loop is an entry control loop which means that the condition is checked before
entering the body of the loop. Therefore, it might be possible that the body of the loop is not
executed even once.

The do while loop
Following is the syntax of the do while loop. The statement in the do blocks are
executed until it reaches the while condition. When the statement reached the condition, the
program will stop executing.
do {
statement;
} while (condition);

Note that there is a semicolon after the while statement. Consider the following code
below which is used to print the statement “Hi!” five times on the screen.

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