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Decisions, Loops, and Arrays

Decisions, Loops, and Arrays. Achmad Arwan, S.Kom. IF Statements. In PHP we have the following conditional statements: if statement - use this statement to execute some code only if a specified condition is true

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Decisions, Loops, and Arrays

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  1. Decisions, Loops, and Arrays Achmad Arwan, S.Kom

  2. IF Statements • In PHP we have the following conditional statements: • if statement - use this statement to execute some code only if a specified condition is true • if...else statement - use this statement to execute some code if a condition is true and another code if the condition is false • if...elseif....else statement - use this statement to select one of several blocks of code to be executed • switch statement - use this statement to select one of many blocks of code to be executed

  3. The IF Statements • The if Statement • Use the if statement to execute some code only if a specified condition is true. • Syntax • if (condition) code to be executed if condition is true; • <html><body><?php$d=date("D");if ($d=="Fri") echo "Have a nice weekend!";?></body></html>

  4. The if...else Statement • Use the if....else statement to execute some code if a condition is true and another code if a condition is false. • if (condition)code to be executed if condition is true;elsecode to be executed if condition is false;<html><body><?php$d=date("D");if ($d=="Fri")  echo "Have a nice weekend!";else  echo "Have a nice day!";?></body></html>

  5. The if...else Statement • If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces: • <html><body><?php$d=date("D");if ($d=="Fri")  {  echo "Hello!<br />";  echo "Have a nice weekend!";  echo "See you on Monday!";  }?></body></html>

  6. The if...elseif....else Statement • Use the if....elseif...else statement to select one of several blocks of code to be executed. • if (condition)code to be executed if condition is true;elseif (condition)code to be executed if condition is true;elsecode to be executed if condition is false; <html><body><?php$d=date("D");if ($d=="Fri")  echo "Have a nice weekend!";elseif ($d=="Sun")  echo "Have a nice Sunday!";else  echo "Have a nice day!";?></body></html>

  7. The PHP Switch Statement • Use the switch statement to select one of many blocks of code to be executed. • switch (n){case label1:code to be executed if n=label1;  break;case label2:code to be executed if n=label2;  break;default:code to be executed if n is different from both label1 and label2;} <html><body><?php$x=1;switch ($x){case 1:  echo "Number 1";  break;case 2:  echo "Number 2";  break;case 3:  echo "Number 3";  break;default:  echo "No number between 1 and 3";}?></body></html>

  8. PHP Loops • In PHP, we have the following looping statements: • while - loops through a block of code while a specified condition is true • do...while - loops through a block of code once, and then repeats the loop as long as a specified condition is true • for - loops through a block of code a specified number of times • foreach - loops through a block of code for each element in an array

  9. The while Loop • The while loop executes a block of code while a condition is true. Syntax • while (condition)  {  code to be executed;  } <html><body><?php$i=1;while($i<=5)  {  echo "The number is " . $i . "<br />";  $i++;  }?></body></html>

  10. The do...while Statement • The do...while statement will always execute the block of code once, it will then check the condition, and repeat the loop while the condition is true. Syntax • do  {  code to be executed;}while (condition); <html><body><?php$i=1;do  {  $i++;  echo "The number is " . $i . "<br />";  }while ($i<=5);?></body></html>

  11. The for Loop • The for loop is used when you know in advance how many times the script should run. Syntax • for (init; condition; increment)  {code to be executed;  } • Parameters: • init: Mostly used to set a counter (but can be any code to be executed once at the beginning of the loop) • condition: Evaluated for each loop iteration. If it evaluates to TRUE, the loop continues. If it evaluates to FALSE, the loop ends. • increment: Mostly used to increment a counter (but can be any code to be executed at the end of the iteration) <html><body><?phpfor ($i=1; $i<=5; $i++)  {  echo "The number is " . $i . "<br />";  }?></body></html>

  12. The foreach Loop • The foreach loop is used to loop through arrays. Syntax • foreach ($array as$value)  {code to be executed;  } • For every loop iteration, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop iteration, you'll be looking at the next array value. <html><body><?php$x=array("one","two","three");foreach ($x as $value)  {  echo $value . "<br />";  }?></body></html>

  13. Arrays • An array is a set of variables that all have the same name but a different index. • Each member of the array is called an element. • Each element's name must be followed by its index in square brackets: • $nama[1]=“Adi”; • $nama[2]=“Dina”;

  14. Initialization of Arrays • $author[0]="William Shakespeare"; • $author = array ("William Shakespeare", "Franz Kafka"); • $author = array (1=>"William Shakespeare", "Franz Kafka"); • $author = array (“wl”=>"William Shakespeare", “Fk”=>"Franz Kafka");

  15. Iterating through an Array • for ($counter=1; $counter<51; $counter++) { echo"<BR>$author[$counter]"; } • Or • $counter = 1; • while ($counter < 51) { • echo"<br> $author[$counter]"; • $counter = $counter + 1; • }

  16. current() and key() Functions • PHP uses a pointer to keep track of which element it's at when it moves through an array. • The pointer indicates the element that is currently being used by the script. • You can use the current() function to view the value of that element. • you can use the key() function to find out its index value. (Key is another name for index.)

  17. current() and key() sample • $director[4]="Orson Welles"; $director[1]="Carol Reed"; $director[93]="Fritz Lang"; $director[24]="Jacques Tourneur"; $current_index_value = key($director); echo ($current_index_value); $current_contents = current($director); echo ($current_contents);

  18. next() and prev() Functions • These functions enable you to navigate through arrays by moving the pointer to the next or previous element in the array. • next()  move to next array • previous()  move to previous array

  19. next() and prev() Functions $director[4]="Orson Welles"; $director[1]="Carol Reed"; $director[93]="Fritz Lang"; $director[24]="Jacques Tourneur"; $director[]="Alfred Hitchcock"; next($director); $current_index_value = key($director); echo ($current_index_value); prev($director); $current_index_value = key($director); echo ($current_index_value);

  20. list() and each() Functions • use the list() and each() functions to return only the elements in the array that contain data. • Syntax while (list($element_index_value, $element_contents) = each($director)) { echo "<br>$element_index_value - $element_contents"; }

  21. list() and each() Functions sample • $director[4]="Orson Welles"; $director[1]="Carol Reed"; $director[93]="Fritz Lang"; $director[24]="Jacques Tourneur"; • while (list($MickeyMouse, $DonaldDuck) = each ($Director)) { echo "<BR>$MickeyMouse - $DonaldDuck"; }

  22. sort() function • sort() is the most basic of the sorting functions. It takes the contents of the array and sorts them into alphabetical order. • The function requires only an array name to sort the array: • sort(ArrayName)

  23. sort() sample <?php $director = array ("Orson Welles","Carol Reed", "Fritz Lang", "Jacques Tourneur"); echo “Before sort”; while (list($IndexValue, $DirectorName) = each ($Director)){ echo "<BR>$IndexValue - $DirectorName"; } sort($director); echo “Before sort”; while (list($IndexValue, $DirectorName) = each ($Director)){ echo "<BR>$IndexValue - $DirectorName"; } ?>

  24. Multidimentional array <?php$shop = array( array( Title => "rose",                       Price => 1.25,                      Number => 15                     ),               array( Title => "daisy",                       Price => 0.75,                      Number => 25,                    ),               array( Title => "orchid",                       Price => 1.15,                      Number => 7                     )             );?>

  25. Multidimentional Arrays <?php echo "<h1>Manual access to each element</h1>";echo $shop[0][0]." costs ".$shop[0][1]." and you get ".$shop[0][2]."<br />";echo $shop[1][0]." costs ".$shop[1][1]." and you get ".$shop[1][2]."<br />";echo $shop[2][0]." costs ".$shop[2][1]." and you get ".$shop[2][2]."<br />";echo "<h1>Using loops to display array elements</h1>";echo "<ol>";for ($row = 0; $row < 3; $row++){    echo "<li><b>The row number $row</b>";    echo "<ul>";    for ($col = 0; $col < 3; $col++)    {        echo "<li>".$shop[$row][$col]."</li>";    }    echo "</ul>";    echo "</li>";}echo "</ol>";?>

  26. <?php echo “Thanks”; ?>

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