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PHP Exercises: Compute the sum of the three given integers. However, if any of the values is in the range 10..20 inclusive then that value counts as 0, except 13 and 17

PHP Basic Algorithm: Exercise-56 with Solution

Write a PHP program to compute the sum of the three given integers. However, if any of the values is in the range 10..20 inclusive then that value counts as 0, except 13 and 17.

Sample Solution:

PHP Code :

<?php
function test($x, $y, $z)
{
  return fix_num($x) + fix_num($y) + fix_num($z);
}


function fix_num($n)
  {
      return (($n < 13 && $n > 9) || ($n > 17 && $n < 21)) ? 0 : $n;
  }
        
echo (test(4, 5, 7))."\n";
echo (test(7, 4, 12))."\n";
echo (test(10, 13, 12))."\n";
echo (test(17, 12, 18))."\n";

Sample Output:

16
11
13
17

Flowchart:

Flowchart: Compute the sum of the three given integers. However, if any of the values is in the range 10..20 inclusive then that value counts as 0, except 13 and 17.

PHP Code Editor:

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Previous: Write a PHP program to compute the sum of the three integers. If one of the values is 13 then do not count it and its right towards the sum.
Next: Write a PHP program to check two given integers and return the value whichever value is nearest to 13 without going over. Return 0 if both numbers go over.

What is the difficulty level of this exercise?



PHP: Tips of the Day

$GLOBALS: An associative array containing references to all variables which are currently defined in the global scope of the script. The variable names are the keys of the array

Example:

<?php
$myGlobal = "global"; // declare variable outside of scope
function test()
{
$myLocal = "local"; // declare variable inside of scope
 // both variables are printed
 var_dump($myLocal);
 var_dump($GLOBALS["myGlobal"]);
}
test(); // run function
// only $myGlobal is printed since $myLocal is not globally scoped
 
var_dump($myLocal);
var_dump($myGlobal); 
?>

Output:

string(5) "local"
string(6) "global"
NULL
string(6) "global"

In the above example $myLocal is not displayed the second time because it is declared inside the test() function and then destroyed after the function is closed.

Becoming global

To remedy this there are two options.

Option one: global keyword

function test()
{
 global $myLocal;
 $myLocal = "local";
 var_dump($myLocal);
 var_dump($GLOBALS["myGlobal"]);
}

The global keyword is a prefix on a variable that forces it to be part of the global scope.

Note that you cannot assign a value to a variable in the same statement as the global keyword. Hence, why I had to assign a value underneath. (It is possible if you remove new lines and spaces but I don't think it is neat. global $myLocal; $myLocal = "local").

Option two: $GLOBALS array

function test()
{
 $GLOBALS["myLocal"] = "local";
 $myLocal = $GLOBALS["myLocal"];
 var_dump($myLocal);
 var_dump($GLOBALS["myGlobal"]);
}

In this example I reassigned $myLocal the value of $GLOBAL["myLocal"] since I find it easier writing a variable name rather than the associative array.