<?php
        echo "Hello World - Printed using php";

        // dynamically allocated variables 
        $variable1 = 4;
        $variable2 = 5;
        
        echo $variable1;
        echo $variable2;

        echo $variable1 + $variable2;
        Echo $variable1 + $variable2;


        // Operators in PHP
        // Arithmrtic Operators
        echo "<h1>Arithmetic Operators</h1>";
        echo "Addition <br>";
        echo $variable1 + $variable2;

        echo "Sybtraction <br>";
        echo $variable1 - $variable2;

        echo "Multiplication <br>";
        echo $variable1 * $variable2;

        echo "Division <br>";
        echo $variable1 / $variable2;
        echo "<br>";


        // Assignment Operators
        echo "<h1>Assignment Operators</h1>";
        echo "The first variable was ";
        echo $variable1;

        echo "<br>";
        echo "The second variable was ";
        echo $variable2;
        echo "<br>";


        $newvariable=$variable1;

        echo "The new variable is ";
        echo $newvariable;
        echo "<br>";

        // $newvariable /= 2;
        // $newvariable *= 2;
        $newvariable *= 2;
        echo $newvariable;


        // Comparison Operators
        echo "<h1> Comparison Operators</h1>";
        echo "<br>";

        echo "The value of 1 == 4 is ";
        echo var_dump(1 == 4);
        echo "<br>";

        echo "The value of 1 != 4 is ";
        echo var_dump(1 != 4);
        echo "<br>";

        echo "The value of 1 >= 4 is ";
        echo var_dump(1 >= 4);
        echo "<br>";

        echo "The value of 1 <= 4 is ";
        echo var_dump(1 <= 4);
        echo "<br>";

        // Increment/Decrement Operators
        echo "<h1> Increment/Decrement Operators </h1> <br> ";
        $new_variable = 5;
        echo "The variable is ";
        echo $new_variable;
        echo "<br>";


        ++$new_variable;
        echo $new_variable;
        echo "<br>";

        --$new_variable;
        --$new_variable;
        echo $new_variable;
        echo "<br>";

        $new_variable++;
        $new_variable++;
        echo $new_variable;
        echo "<br>";

        $new_variable--;
        $new_variable--;
        echo $new_variable;
        echo "<br>";

        // Logical Operators
        // and (&&)
        // or (||)
        // xor (^)
        // not (!)
        echo "<h1> Logical Operators </h1>";
        echo var_dump(true && true);
        echo var_dump(true and false);

        echo "<br>";

        echo var_dump(true || false);
        echo var_dump(true or true);

        echo "<br>";

        $my_var = 2^4;
        echo $my_var;

        echo var_dump(2 xor 6 );
    ?>

    <?php
        define("PI" , 3.14);
        // Datatypes in php
        // 1. String 
        // 2. Integer 
        // 3. Float 
        // 4. Boolean 
        // 5. Array
        // 6. Object

        echo "<h1> DATA - TYPES </h1>";

        $new_string = "This is a string";
        echo "<br>";
        echo var_dump($new_string);

        echo '<br>';
        $new_string = 67;
        echo "<br>";
        echo var_dump($new_string);

        echo '<br>';
        $new_string = 67.23;
        echo "<br>";
        echo var_dump($new_string);


        echo '<br>';
        $new_string = true;
        echo "<br>";
        echo var_dump($new_string);


        // constants 
        // defined on top;
        echo "<br>";
        echo PI;
        echo "<br>";
    ?>

    <?php
        echo "<h1> If else </h1>". "<br>";
        $age = 6;
        if($age>18){
            echo "You can go to the party";
        }
        else if($age==7){
            echo "You are 7 years old";
        }
        else if($age==6){
            echo "You are 6 years old";
        }
        else{
            echo "You can not go to the party";
        }

        echo "<h1>ARRAYS</h1>"."<br>";
        // Arrays in php
        $languages = array("Python", "C++", "php", "NodeJs"); 
        // echo count($languages);   
        // echo $languages[0];   

        echo "<h1>LOOPS</h1>"."<br>";
        // Loops in PHP
        $a = 0;
        while ($a <= 10) {
            echo "<br>The value of a is: ";
            echo $a;
            $a++;
        }

        // Iterating arrays in PHP using while loop
        $a = 0;
        while ($a < count($languages)) {
            echo "<br>The value of language is: ";
            echo $languages[$a];
            $a++;
        }

        echo "<h1>WHILE LOOP</h1>"."<br>";
        // Do while loop
        $a = 200;
        do {
            echo "<br>The value of a is: ";
            echo $a;
            $a++;
        } while ($a < 10);

        echo "<h1>USING FOR LOOP</h1>"."<br>";
        // For loop
        for ($a=60; $a < 10; $a++) { 
            echo "<br>The value of a from the for loop is: ";
            echo $a;
        }

        echo "<h1>USING FOREACH</h1>"."<br>";
        foreach ($languages as $value) {
            echo "<br>The value from foreach loop is ";
            echo $value;
        }

        
        echo "<h1>USING FUNCTIONS</h1>"."<br>";
        function print5(){
            echo "FIVE";
        }
        print5();
        print5();
        print5();
        print5();
        function print_number($number){
            echo "<br>Your number is ";
            echo $number;
        }
        print_number(45);
        print_number(435);
        print_number(5);
    ?>

    <?php
        $str = "This this this";
        
        echo "<h1>CONCATENING TWO STRINGS USING .</h1>"."<br>";
        echo $str. "<br>";

        echo "<h1>CALCULATING THE LENGTH OF THE STRING </h1>"."<br>";
        $lenn = strlen($str);
        echo "The length of this string is ". $lenn . ". Thank you <br>";


        echo "<h1>CALCULATING THE NUMBER OF WORDS IN A STRING</h1>"."<br>";
        echo "The number of words in this string is ". str_word_count($str) . ". Thank you <br>";

        echo "<h1>REVERSING THE STRING</h1>"."<br>";
        echo "The reversed string is ". strrev($str) . ". Thank you <br>";

        echo "<h1>FINDING A SUBSTRING IN A STRING</h1>"."<br>";
        echo "The search for is in this string is ". strpos($str, "is") . ". Thank you <br>";

        echo "<h1>REPLACING ONE SUBSTRING OF STRING WITH ANOTHER</h1>"."<br>";
        echo "The replaced string is ". str_replace("is", "at", $str) . ". Thank you <br>";
        // echo $lenn;

    ?>