While Loop

PHP while loops are similar to for loops, but with a different structure. Personally, I use for loops much more often than I use while loops. However, while loops have their own powerful uses that you will discover later in your programming life.

Example

$i = 0;
while($i < 5)
{

echo $i; //write our variable’s value
echo "<br/>"; //line break
$i++; //increment operator

}
echo "End of while loop";

Result

0
1
2
3
4
End of while loop

After seeing the while loop, you can probably see how it is like the for loop, but just with the first statement is outside of the loop, the conditional remains in the if like statement, and the second statement is embedded in an if like statement.

The first statement $i = 0; is simply setting our variable $i equal to zero. The conditional statement $i < 5 is holding down the fort as the only item in the if like statement. Finally, we get into the embedded code where our increment operator, $i++;, serves to advance the if like statement. From the results, we can see that the exact same thing happens here that happened in the previous for loop.

Example

$i = 0;
do
{

echo $i; //write our variable’s value
echo "<br/>"; //line break
$i++; //increment operator

}
while($i < 5)

Result

0
1
2
3
4

Again, pretty similar to the example above, but there is actually one major difference. In the do while loop, the statements in the do while are always run once because the conditional is at the end. The conditional here tells the server to go back and run through the do part again. We set the variable $i equal to 0. Then, we run through the do part where we find our increment operator $i++;. The results are the same as the previous loops. Once the increment operator makes $i equal to five, we exit the loop and continue reading onto the next statement, echo ” End of while loop “;.

PHP while loop iteration

The image above shows how PHP loops or iterates through a while loop. If the condition is met, PHP executes the code in the parentheses after the while loop. After executing that code, PHP returns to the while loop condition and checks to see if the condition is true. If is it true, the code in the while loop is executed again. This process continues until the condition is no longer true.

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Leave a Comment

  1. For the 2nd example given, line 4 should be "echo $i" instead of "echo i" to get the given output (as illustrated in the subsequent explanation). The latter gives i’s and not the assigned value for variable i in each iteration.

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