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PHP Exercises: Convert the last 3 characters of a given string in upper case

PHP Basic Algorithm: Exercise-24 with Solution

Write a PHP program to convert the last 3 characters of a given string in upper case. If the length of the string has less than 3 then uppercase all the characters.

Sample Solution:

PHP Code :

<?php
function test($s) 
{
   return strlen($s) < 3 ? strtoupper($s) : substr($s, 0, strlen($s) - 3).strtoupper(substr($s, strlen($s) - 3));
 }


echo test("Python")."\n";
echo test("Javascript")."\n";
echo test("js")."\n";
echo test("PHP")."\n";

Sample Output:

PytHON
JavascrIPT
JS
PHP

Pictorial Presentation:

PHP Basic Algorithm Exercises: Convert the last 3 characters of a given string in upper case.

Flowchart:

Flowchart: Convert the last 3 characters of a given string in upper case.

PHP Code Editor:

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Previous: Write a PHP program to check if two given non-negative integers have the same last digit.
Next: Write a PHP program to create a new string which is n (non-negative integer) copies of a given string.

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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.