Basic knowledge of PHP language

•  PHP Code :- For Partiality and Compatibility always use the long form.

          Long farm :         <?php    Expn     ?>
          Sort form  :         <?          Expn      ?>
         Sort form equivalent of <?    echo    ?>
         Note : No closing semicolon (;) is required <?     Expn      ?>

• Semicolon (;) :- All statement must end in a semicolon (;) otherwise, errors will be generated. If the error doesn't make sense. You probably are missing a semicolon somewhere !

• Single Quotations ('') :-  Single quotes content inside single quotes is evaluated literally.Therefore $ string actually means ( dollar sing ) string and does not represent the variables.

Example:

$string = ' single quoted ';

echo '$string';

• Double Quotes ("") :- Double Quoted variable inside double quotes are evaluated for their value.

Example: 

$string=" double quoted ";

echo "$string";

• Backslash ( Escape character ):- Escapes character that sold be evaluated literally when inside inside double quotation.

Example:  

$string= "double quoted";

echo "\$string is set as $string";

$string is set as double quotes.

• Special characters :-  

Backslash (\)

Question mark (?)

Single Quotes (')

Double Quotes (")

Doller sing ($)

• Comments :-  Single line for everything to the right of the double forward slashes.

// This is a comments.

Multiple line opening and closing tags.

/*        This is a comment      */  

• Formatting Character :-

\n - New Line
\r - Carriage return
\t - Tab
\b - Back space

• Define (name, value [$Boolean]):-

$Boolean - [optional] default: false, case-sensitive define a Constance a set value that is assigned globally making it variable to function and an argument.

Example:    

define('Hello', 'Hello word!' );

echo Hello;

Output: Hello word!

• Function:- Function function name(argument) {},

function can be places only where in a page and will be available even with called above the actual function  being created as part of conditional statement has been evaluated.

Example: 

hello();

// Above the conditional statement this will cause an error 

if(0==0)

{

function hello()

{

echo 'Hello';

}

}

Fatal error: call to undefined function hell()
if(0==0)
{
function hello()
{
echo 'Hello ';
}
}

hello();
there();

function there()
{
echo 'there';
}


Hello there: function can have a argument (as above), argument passed to them, an default arguments with passed argument as optional. The argument names are use within that function as variable name.
Example:
function args($a,$b)
{
// has no default values request to input
echo "a=$a, b=$b";
}
args(1,2);
Output:
a=1,b=2