PHP - The Continue Statement

Learning PHP, MySQL & JavaScript with Jquery, css and html5 - 5th Edition 2018.

Eaxample exercise 4-36. Trapping division-by-zero erros using continue.


In this example we learn about the Continue Statement.
All the code have been tested with PHP Version 7.2.4 on lampp / xampp for linux mint

Here is all the code if you don't bother to read the whole blo

<?php
// Learning Php, MySQL and JavaScript 5th edition
// page 89-90

// Example 4-36. Trapping division-by-zero erros using continue
// $j = 10;
// $iterations = 0;

// while ($j > -10) 
// {
//  $j--;

//  if ($j == 0) continue;
 
//  echo (10 / $j) . "<br>";
// }

// Visual improvement ===============
// $j = 10;
// $iterations = 0;

// while ($j > -10) 
// {
//  $j--;
//  $iterations++;

//  if ($j == 0) continue;
 
//  echo "Loop " . $iterations . " = " . (10 / $j) . "<br>";
// }

// Visual improvement with curly braces and the word "loop" have been replaced with "iteration" 
$j = 10;
$iterations = 0;

while ($j > -10) 
{
 $j--;
 $iterations++;

 if ($j == 0) 
 {
  echo "iteration " . $iterations . ' = $j = 0 <br>';
 }
 else 
 {
  echo "iteration " . $iterations . " = " . (10 / $j) . "<br>";
 }
}
?>

The original code in the book look like this

<?php
$j = 10;

while ($j > -10) 
{
 $j--;

 if ($j == 0) continue;
 
 echo (10 / $j) . "<br>";
}
?>

Browser result:

1.1111111111111
1.25
1.4285714285714
1.6666666666667
2
2.5
3.3333333333333
5
10
-10
-5
-3.3333333333333
-2.5
-2
-1.6666666666667
-1.4285714285714
-1.25
-1.1111111111111
-1

As you can see this will only give you the direct result where it will skip/continue if the $j variable is equal to 0. I like to make the browser output with some text that make the result a bit more visual understandable.

I added some simple visual text improvement

<?php 

$j = 10;
$iterations = 0;

while ($j > -10) 
{
 $j--;
 $iterations++;

 if ($j == 0) continue;
 
 echo "Loop " . $iterations . " = " . (10 / $j) . "<br>";
}

?>

Browser result:

Loop 1 = 1.1111111111111
Loop 2 = 1.25
Loop 3 = 1.4285714285714
Loop 4 = 1.6666666666667
Loop 5 = 2
Loop 6 = 2.5
Loop 7 = 3.3333333333333
Loop 8 = 5
Loop 9 = 10
Loop 11 = -10
Loop 12 = -5
Loop 13 = -3.3333333333333
Loop 14 = -2.5
Loop 15 = -2
Loop 16 = -1.6666666666667
Loop 17 = -1.4285714285714
Loop 18 = -1.25
Loop 19 = -1.1111111111111
Loop 20 = -1

Here you see the result with loop/iteration number but it wont show us where the Continue Statement skiped the number 0

Here is another improment but I removed the Continue Statement in the code to visual show where the variable $j is equal to 0

<?php 

$j = 10;
$iterations = 0;

while ($j > -10) 
{
 $j--;
 $interations++;

 if ($j == 0) 
 {
  echo "Iteration " . $iterations . ' = $j = 0 <br>';
 }
 else 
 {
  echo "Iteration " . $iterations . " = " . (10 / $j) . "<br>";
 }
}

?>

As you can see I change the the word "Loop" to "Iteration" and at "Iteration 10" you can se where variable $j is equal to 0. I know we are using "if else" statement but it's only to show where the Continue Statement would have continue with While loop

Browser result:

 

Iteration 1 = 1.1111111111111
Iteration 2 = 1.25
Iteration 3 = 1.4285714285714
Iteration 4 = 1.6666666666667
Iteration 5 = 2
Iteration 6 = 2.5
Iteration 7 = 3.3333333333333
Iteration 8 = 5
Iteration 9 = 10
Iteration 10 = $j = 0
Iteration 11 = -10
Iteration 12 = -5
Iteration 13 = -3.3333333333333
Iteration 14 = -2.5
Iteration 15 = -2
Iteration 16 = -1.6666666666667
Iteration 17 = -1.4285714285714
Iteration 18 = -1.25
Iteration 19 = -1.1111111111111
Iteration 20 = -1

I know the whole shebang is not correct but it will give a more visualy understanding of how a Continue Statemen works. Sometime it can be hard to understand what you can't see