WDP - Selection Structure and Php Loop

Php

1. Selection Structure
• if statement - executes some code if one condition is true

Syntax

if (condition) {
    code to be executed if condition is true;
}

Example: 

<?php

if ($a > $b)

  echo "a is bigger than b";

?>

• if... else statement - executes some code if a condition is true and another code if that condition is false

Syntax

if (condition) {
    code to be executed if condition is true;
} else {
    code to be executed if condition is false;}

Example

<?php
if ($a > $b) {
  echo "a is greater than b";
} else {
  echo "a is NOT greater than b";
}?>

• if... elseif... else statement - executes different codes for more than two conditions

Syntax

if (condition) {
    code to be executed if this condition is true;} elseif (condition) {
    code to be executed if this condition is true;} else {
    code to be executed if all conditions are false;}

Example

if($a > $b){
    echo $a." is greater than ".$b;
}
elseif($a == $b){
echo $a." is equals to ".$b;
}
else{
echo $a." is neither greater than or equal to ".$b;
}

• switch statement - selects one of many blocks of code to be executed

Syntax

switch (n) {
    case label1:
        code to be executed if n=label1;
        break;
    case label2:
        code to be executed if n=label2;
        break;
    case label3:
        code to be executed if n=label3;
        break;
    ...
    default:
        code to be executed if n is different from all labels;
}

Example

<?php
    $i = "bar";
switch ($i) {
    case "apple":
        echo "i is apple";
        break;
    case "bar":
        echo "i is bar";
break;
    case "cake":
        echo "i is cake";
        break;
}
}?>

1. Php Loops
• while statement - execute a block of code while the specified condition is true.

Syntax

while (condition is true) {
    code to be executed;
}

Example

<?php /* example 1 */
$i = 1;
while ($i <= 10) {
    echo $i++;  /* the printed value would be
                   $i before the increment
                   (post-increment) */}
/* example 2 */
$i = 1;
while ($i <= 10):
    echo $i;
    $i++;
endwhile;?>

• do... while statement - loops through a block of code once, and then repeats the loop as long as the specified condition is true

Syntax

do {
    code to be executed;} while (condition is true);

Example

<?php 
$x = 1; 

do {
    echo "The number is: $x <br>";
    $x++;
} while ($x <= 5);
?>

• for statement -  loops through a block of code a specified number of times

Syntax

for (init counter; test counter; increment counter) {
    code to be executed;
}

Example

for ($i = 1; $i < 10 ; $i++) {
    echo $i;
}

• foreach statement - loops through a block of code for each element in an array

Syntax

foreach ($array as $value) {
    code to be executed;
}

Example

<?php

foreach (array(2, 3, 4, 5) as $value) {

    $value = $value * 2;

echo $value."<br/>";

}

?>