PHP, Structures and Functions, Fundamental Syntaxes

do...while

php128 apg

Full code fragment that perform REPEATED ACTIONS until a desired result is reached.

Behavior do...while loops are the similar to while loops, except the truth expression is checked at the end of each iteration instead of in the beginning.

Since PHP 5.3.0, it is possible to use the goto operator instead of this function.

With the use of goto it will be possible to code scripts with greater ease.

On the next page you will know how to use it.

FIRST SYNTAX TYPE

In the following, we will show the FIRST SYNTAX TYPE of - do... while - conditional structure:


<?php

// STRUCTURE #1

seed
    do 
    statement
    
    while ( expr );
    
    
    where,

seed = to begin the loop

statement = code to be executed

expr = to control the loop
    
?>

SECOND SYNTAX TYPE

In the following, we will show the SECOND SYNTAX TYPE of - do... while - conditional structure:


<?php

// STRUCTURE #2
 
    seed
        do
        {
            statement
        }
        while ( expr );


where,

seed = to begin the loop

statement = code to be executed

expr = to control the loop
             
?>

EXERCISE


<?php

$n01 = 2;

do 
echo $n01++ . '&nbsp;&nbsp;';
while ($n01 <= 9);

?>

RESULT

2 3 4 5 6 7 8 9

EXERCISE


<?php

$lang = 'en';
// $lang = 'pt';

$nr = 5;
$ir = 1; 
$dr = $nr - $ir + 1;
$txt = 'Maxima debetur puero reverentia!';
$en = $txt . "<br> $dr times -> from $ir 
                       to $nr -> interval [$ir, $nr]<br><br>";
$pt = $txt . "<br> $dr vezes -> de $ir 
                        a $nr -> intervalo [$ir, $nr]<br><br>";

echo $$lang;
do {
print $ir;
echo ") $txt<br><br>";
$ir++;
}
while ( $ir <= $nr );

?>

RESULT

Maxima debetur puero reverentia!
5 times -> from 1 to 5 -> interval [1, 5]

1) Maxima debetur puero reverentia!
2) Maxima debetur puero reverentia!
3) Maxima debetur puero reverentia!
4) Maxima debetur puero reverentia!
5) Maxima debetur puero reverentia!

EXERCISE


<?php

$n3 = 0;

do
echo ++$n3 . ' * ' . ($n3 - 1) . ' = ' . $n3*($n3 - 1) . '<br>';
while($n3 <= 9)

?>

RESULT

1 * 0 = 0
2 * 1 = 2
3 * 2 = 6
4 * 3 = 12
5 * 4 = 20
6 * 5 = 30
7 * 6 = 42
8 * 7 = 56
9 * 8 = 72
10 * 9 = 90