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While Loop |
While Loop
The while
loop repeatedly executes the block of statements until the condition specified within the parentheses evaluates to false
. For instance:
while (some_condition_is_true)
{
// do something
}
Each 'iteration' (of executing the block of statements) is preceeded by the evaluation of the condition specified within the parentheses - The statements are executed only if the condition evaluates to true
. If it evaluates to false
, the execution of the program resumes from the the statement just after the while
block.
Note: For the while
loop to start executing, you'd require the condition to be true
initially. However, to exit the loop, you must do something within the block of statements to eventually reach an iteration when the condition evaluates to false
(as done below). Otherwise the loop will execute forever. (In practice, it will run until the JVM runs out of memory.)
Example
In the following example, the expression
is given by iter_While < 10
. We increment iter_While
by 1
each time the loop is executed. The while
loop breaks wheniter_While
value reaches 10
.
int iter_While = 0;
while (iter_While < 10)
{
System.out.print(iter_While + " ");
// Increment the counter
// Iterated 10 times, iter_While 0,1,2...9
iter_While++;
}
System.out.println("iter_While Value: " + iter_While);
Output:
0 1 2 3 4 5 6 7 8 9
iter_While Value: 10