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PHP Constructs

PHP Constructs. Advance Database Management Systems Lab no.3. LAB Outline. PHP Loops PHP Functions Practice of PHP Array functions from previous Lab. PHP Loops. While loops through a block of code while a specified condition is true do...while

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PHP Constructs

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  1. PHP Constructs Advance Database Management Systems Lab no.3

  2. LAB Outline • PHP Loops • PHP Functions • Practice of PHP Array functions from previous Lab

  3. PHP Loops • 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

  4. While Loop • Syntax while (condition)  {  code to be executed;  } • Example <?php $i=1; while($i<=5)   {   echo "The number is " . $i . "<br />";   $i++;   }?>

  5. While Loop • Output of the example code The number is 1The number is 2The number is 3The number is 4The number is 5

  6. Do While Loop • Syntax do  {  code to be executed;}while (condition); • Example <?php$i=1;do  {  $i++;  echo "The number is " . $i . "<br />";  }while ($i<=5); ?>

  7. Do While Loop • Output of the example code The number is 2The number is 3The number is 4The number is 5The number is 6

  8. For Loop • Used when number of times a code/script (to be executed) is known in advance • 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)

  9. For 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 loop) • Note: Each of the loop parameters can be empty, or have multiple expressions (separated by commas)

  10. For Loop • Example <?phpfor ($i=1; $i<=5; $i++)  {  echo "The number is " . $i . "<br />";  }?> • Output The number is 1The number is 2The number is 3The number is 4The number is 5

  11. For Each Loop • It is used to loop throuh 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.

  12. For Each Loop • Example <?php$x=array("one","two","three");foreach ($x as $value)  {  echo $value . "<br />";  } ?> • Output onetwothree

  13. PHP Functions • In PHP, there are more than 700 built-in functions. • A function will be executed by function call. • You may call a function from anywhere within a page. • The function name can start with a letter or underscore (not a number)

  14. PHP Functions • An important use of function • To keep the browser from executing a script when the page loads, you can put your script into a function.

  15. Creating a PHP Function • Syntax function functionName(){code to be executed;} • Example <?phpfunction writeCourse(){echo “Advanced DBMS";}echo “Course name is ";writeCourse(); ?>

  16. Adding Parameters to Functions • A parameter is just like a variable. • They are specified after the function name, inside the parentheses • A function can take one or more parameters.

  17. Example Concatenation operator • <html><body> <?phpfunction writeChocoName($name){echo $name . " Chocolate. <br />";} echo “The best is "; writeChocoName(“Milk");echo “Some people also like "; writeChocoName(“Dark");echo “Few may like "; writeChocoName(“White"); ?> </body> </html> Part of text

  18. Output The best is Milk Chocolate. Some people also like Dark Chocolate. Few may like White Chocolate.

  19. Another Example (2 parameters) • <html><body> <?phpfunction sum($x, $y){echo $x+$y ; }echo “The total score is: "; sum(10, 20);?> </body> </html> Output: The total score is 30

  20. Function Returning Value • <html><body><?phpfunction add($x,$y){$total=$x+$y;return $total;} echo "1 + 16 = " . add(1,16);?></body></html> Output: 1 + 16 = 17

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