PRACTICAL 2:
THEORY
In this web page, we will study and implement basics syntax of php.
IMPORTANT TAGS & ATTRIBUTES:
Basic Syntax: When PHP parses a file, it looks for
opening and closing tags, which are <?php and ?> which tell PHP to start
and stop interpreting the code between them. Parsing in this manner allows PHP
to be embedded in all sorts of different documents, as everything outside of a
pair of opening and closing tags is ignored by the PHP parser.
E.x.
<?php content ?>
Data types: Although variables are not declared to
be type-specific in PHP, PHP still has a common set of data types: Boolean,
integer, float, string, array, object, resource, NULL
Determining the current type of a variable: A
series of type-testing functions exist to determine the current type of
variables:
gettype(varname): returns type name, such as
'string'
similarly, is_int()
is_integer() is_long() is_null() is_numeric()
is_object() is_real() is_string() is_scalar() is_bool()
empty() isset()
Variables: Variables in PHP are represented by a
dollar sign followed by the name of the variable. The variable name is
case-sensitive. A valid variable name starts with a letter or underscore,
followed by any number of letters, numbers, or underscores.
E.x. $var = "Bob";
$Var =
"Joe"; // different variable
Function: A function may be defined using syntax
such as the following:
E.x.
<?php
function foo($arg_1, $arg_2, /* ..., */ $arg_n)
{
echo "Example function.\n";
return $retval;
}
?>
Any valid PHP code may appear inside a function,
even other functions and class definitions.
Function names follow the same rules as other
labels in PHP. A valid function name starts with a letter or underscore,
followed by any number of letters, numbers, or underscores.
Array: An array can be created using the array()
language construct. It takes any number of commaseparated key => value pairs
as arguments.
array( key =>
value, key2 =>
value2, key3 => value3,
...
)
The comma after the last array element is optional
and can be omitted. This is usually done for singleline arrays, i.e. array(1,
2) is preferred over array(1, 2, ). For multi-line arrays on the other hand the
trailing comma is commonly used, as it allows easier addition of new elements
at the end.
Superglobal: The $GLOBALS array is an associative
array with the name of the global variable being the key and the contents of
that variable being the value of the array element. Notice how $GLOBALS exists
in any scope, this is because $GLOBALS is a superglobal. Here's an example
demonstrating the power of superglobals:
E.x.
<?php
function test_superglobal()
{
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NAME:AYUSH SINGLA
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