Programming and Problem Solving with Java

(^224) | File Objects and Looping Statements
loopCount = 1; // Initialization
while(loopCount <= 10) // Test
{
.

. // Repeated actions
.
loopCount = loopCount + 1; // Incrementation
}

Here loopCountis the loop control variable. It is set to 1 before loop entry. The whilestate-

ment tests the expression

loopCount <= 10

and executes the loop body as long as the expression is true. The dots inside the compound

statement represent a sequence of statements to be repeated. The last statement in the loop

body increments loopCountby adding 1 to it.

Look at the statement in which we increment the loop control variable. Notice its form:

variable = variable + 1;

This statement adds 1 to the current value of the variable, and the result replaces the old value.

Variables that are used this way are called counters. In our example,loopCountis incremented

with each iteration of the loop—we use it to count the iterations. The loop control variable

of a count-controlled loop is always a counter.

We’ve encountered another way of incrementing a variable in Java. The incrementation

operator (++) increments the variable that is its operand. Thus the statement

loopCount++;

has precisely the same effect as the assignment statement

loopCount = loopCount + 1;

From here on, we will typically use the ++operator, as do most Java programmers.

When designing loops, it is the programmer’s responsibility to see that the condition to

be tested is set correctly (initialized) before the whilestatement begins. The programmer

also must make sure that the condition changes within the loop so that it eventually becomes

false; otherwise, the loop will never be exited.

loopCount = 1; // Variable loopCount must be initialized

while(loopCount <= 10)

{

.

.

.

loopCount++; // loopCount must be incremented

}