PHP Lecture 3.....

>> String Interpolation..

String Interpolation is a quick shortcut, allowing to pop the value of a variable into a double quoted string. Ex:- <?php

$value =10;

echo "Value is: $value";

?>

>>Rules

1. Surround the variable name with spaces.

    Ex:- <?php

               $value=10;

               echo"$value is good for you";

               ?>

2. Don't use single quotation marks - when you use single quotation marks , PHP does not apply string interpolation.

>> Constants In PHP....

1. Whose values can't be modified.

2. define() function is used to create a constant.

3. Syntax:- define("constant_variable", value, case-insensitive);

     Ex:- a.) define("pi", 3.14);    [Here "pi" is case sensitive]

             b.) define("pi", 3.14, TRUE);    [Here "pi" is non-case sensitive]

             c.) define("site", "anime");

>> RULES...

• No need to start constant variable name with '$' sign.
• Name only starts with a letter and an underscore(_).
• Variable name cannot start with a number.
• It is case sensitive which implies that the variable num in lowercase is different from variable NUM in uppercase. But we can make it case insensitive.
• Constants are automatically global and can be used across the entire script.
• Can't use predefined constant name. e.g:- PHP_VER, PHP_anime etc.
• Can't use reserved keywords. eg:- else, if, etc.

>>Arithmetic/Math Operators...

Eg:-...

           <?php

            echo 5+6;

            echo 6-2;

            echo 6/3;

            echo 7*1;

            echo 6%2;

            ?>