Introduction to php contains basic....pptx

■ Origins and uses of PHP
■ Overview of PHP
■ General Syntactic Characteristics
■ Primitives
■ Operations and Expressions
■ Output
■ Control Statements

Origins and uses of PHP
• PHP was developed by Rasmus Lerdorf a member
of the Apache Group.
• In 1995 Lerdorf originally named it Personal Home
Page (PHP) but currently is known asHypertext
Preprocessor.
• PHP is a server-side, scripting language executed on
the server.
• PHP is a widely used, open-source scripting language .

Overview of PHP
PHP processor has two modes of operations:
1. Copy mode :
On the server side when the PHP processor finds XHTML code in the input
file, it simply copies it to the output file.
2. Interpret mode:
On the server side when it encounters a PHP script in the input file, it
interprets it and sendsany output of the script to the output file.

General Syntactic Characteristics
• PHP scripts can be embedded within the XHTML document by enclosing
it between the <?php and ?> tags.
• Example:
<!DOCTYPE html>
<html>
<body>
<? php
// single-line comment
# single-line comment
/*
multiple-lines
comment block
*/
echo “Hello World”;
?>
</body>
</html>

PHP allows comments to be specified in three different ways:
• Single-line comments can be specified either with # or with //.
• Multiple-line comments are delimited with /* and */ , as in many other
programming languages.
• PHP statements are terminated with semicolons(;).
• All variables in PHP begin with dollar sign($) followed by the name of the
variable. The variable names are case sensitive, $age and $Age are not same.
• Variables are not declared in PHP; they have a value and the type of the value.

• A variable name cannot start with a number. A variable name can only contain
alpha-numeric characters and underscores (A-z, 0-9, and _ ).
• A variable name must start with a letter or the underscore character.

• Reserved words of PHP
• Although variable names in PHP are case sensitive, neither reserved words nor
function names are
• For example,
there is no difference between while, WHILE, While, wHile.

Primitives, operations and expressions
• PHP has four scalar data types:
-Boolean
- Integer
-Double and
-String
• PHP has two compound data types:
- Array
- Object
• PHP has two special types:
-Resource
-NULL

• Integer type:
-PHP integer is corresponds to long in C, it is usually 32 bits.
• Double type:
-PHP's double type corresponds to C's double type.
-It can have a decimal point, exponent or both.
-There does not need to be any digits before or after the decimal point, both
are legal. EX: .345 345.
• String type:
-String literals are defined with either single (’) or double quotes (")
delimiters.

• In single quoted string literals, escape characters such as n, are not
recognized as anythingspecial and the values of embedded variables are
not substituted.
• In double-quoted string literals, escape sequences are recognized and
embedded variables arereplaced by their current values.
• Ex:
• Boolean type
Boolean values are either TRUE or FALSE, both of which are case
insensitive.

Output
• echo and print are both used to output data to the screen.
• echo has no return value and can take multiple parameters. print has return value
1 and cannot take multiple parmeters.
Ex:

Control Statements
• The control structures in PHP are very similar to C/C++/Java.
• The control statements include:
- if and if-else
-switch
- while and do-while
- for and foreach

If-elseif-else
• This statement executes different codes for more
than two conditions.
• EX: <?php
if ($x > $y)
{ echo "x is bigger than y"; }
elseif ($x == $y)
{ echo "x is equal to y"; }
else
{ echo "x is smaller than y"; }
?>

switch statement
• The switch statement is used to perform different action based on different
conditions.
• Example:
<?php
$x = 2;
switch ($x) {
case 1:printf("Choice is 1");
break;
break;
break;
default:printf("Choice other than 1, 2 and 3");
}
?>

While loop
• The while loop excute the
statement until the specified
condition is true.
• Ex:
<html>
<body>
<?php
$x = 1;
while($x <= 5) {
echo " $x ";
$x++;
}
?>
</body>
</html>
Do while loop
• It excutes the block of the code
and then check for the condition.
• Ex:
<html>
<body>
<?php
$x = 1;
do {
echo " $x ";
$x++;
} while ($x <= 5);
?>
</body>
</html>

For loop
• For loop is a control structure that repeats a block of code as long as a condition
is met. It's usually used to repeat a block of code a certain number of times.
• Example:
<!DOCTYPE html>
<html>
<body>
<?php
for ($x = 0; $x <= 10; $x++) {
echo "The number is: $x <br>";
}
?>
</body>
</html>

for-each
• The foreach loop works only on array and is used to loop through each
key/value pair in array.
• Example:

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