Chap1introppt2php(finally done)

INTRODUCTION
TO PHP
1Monica Deshmane(H.V.Desai College, Pune)

Language Basics:PHPData types
Java is strongly typed once you've created a
variable, you can't change the type of data stored in
it.
PHP, in contrast, is loosely typed you can change a
variable's data type at any time.
PHP provides eight types of values.
Four are scalar,
two are compound types,
and two are special types.
(Building blocks of
PHP)

Language Basics:PHPData types (Building blocks of PHP)
1. Scalar types:
Integers
Floating-point numbers
Strings
Booleans
2. Compound types:
Arrays
Objects
3. Special types:
Resource
NULL
Data types

1. ScalarData types
Integers are whole numbers, like 1, 12, and 256.
The range of acceptable values varies according to the
details of your platform but typically extends from -
2,147,483,648 to +2,147,483,647.
Integer literals can be written in decimal, octal, or
hexadecimal.
Decimal values are represented by a sequence of digits,
without leading zeros. The sequence may begin with a plus (+)
or minus (-) sign. If there is no sign, positive is assumed.
e.g. 1998, -641, +33
is_int( ) function (or its is_integer( ) alias) to test whether a
value is an integer:
if (is_int($x)) { // $x is an integer }
Integer

1. ScalarData types
Floating-point numbers are also called real numbers.
They are numbers that have a fractional component.
PHP floating-point numbers are equivalent to the double
data type.
PHP recognizes two types of floating point numbers.
i. The first is a simple numeric literal with a decimal
point. e.g. 3.14, 0.017, -7.1
ii. The second is a floating-point number written in
scientific notation as [number]E[exponent], e.g.
1.75E-2.
Use the is_float( ) function (or its is_real( ) alias) to test
whether a value is a floating point number:
if (is_float($x)) { // $x is a floating-point number }
Floating-
Point
Numbers

1. ScalarData types
String
A string is a text literal of an arbitrary length.
A string is indicated by being enclosed in quotes,
either double or single quotes.
Variables are expanded within double quotes,
while within single quotes they are not:
e.g.
$name = “Smith";
echo "Hi, $namen";
echo 'Hi, $name';
O/P:
Hi, Smith

1. ScalarData types
StringA single-quoted string only recognizes to get a literal
backslash and ' to get a literal single quote:
e.g.
$dos_path = 'C:WINDOWSSYSTEM';
$publisher = 'Tim O'Reilly';
echo "$dos_path $publishern";
Output: C:WINDOWSSYSTEM Tim O'Reilly
To test whether two strings are equal, use the ==
comparison operator:
e.g. if ($a == $b) { echo "a and b are equal" }
is_string( ) function to test whether a value is a string: if
(is_string($x)) { // $x is a string }
Escape sequences applied.

1. ScalarData types
BooleanA boolean value represents a "truth value"—it says
whether something is true or not. Truth and falseness
determine the outcome of conditional code such as:
if ($alive) { ... }
In PHP, the following values are false:
The integer -> 0
The floating-point value-> 0.0
The empty string-> ("") and the string "0"
An array ->with zero elements
An object ->with no values or functions
The NULL value
is_bool( ) function to test whether a value is a boolean: if
(is_bool($x)) { // $x is a boolean }

2. Compound Data types
ArraysAn array is a variable that holds a group of values. By
referring to their index position we can access the
individual elements.
The position is either specified numerically or by name.
An array with a numeric index is commonly called an
indexed array while one that has named positions is called
an associative array.
In PHP, all arrays are associative, but you can still use a
numeric index to access them.
Referencing array elements:
$arrayName[index];

Arraysis_array( ) function to test whether a value is an array:
if (is_array($x)) { // $x is an array }
indexed array
$item[0] = “Pen"; $item[1] = “Pencil";
$item[2] = “Notebook";
associative array
$book[‘C’] = “Richie”; $book[‘CPP’] = “Bjarne”;
$book[‘Java’] = “Sun”;
The array( ) construct creates an array:
$item = array(‘Pen’, ‘Pencil’, ‘Notebook’);
$book = array(‘C’ => ‘Richie’ , ‘CPP’ => ‘Bjarne’,
‘Java’ => ‘Sun’);

Objects
PHP supports object-oriented programming (OOP).
Classes are the unit of object-oriented design.
A class is a definition of a structure that contains
properties (variables) and methods (functions).
 Classes are defined with the class keyword:
<?php
class Book
{ var $name = '';
function name ($newname = NULL)
{ if (! is_null($newname))
{ $this->name = $newname; }
return $this->name;
}
}

Objects
Once a class is defined, any number of objects
can be made from it with the new keyword,
and the properties and methods can be accessed
with the -> construct:
Ex. $b1 = new Book;
$b1->name('C');
printf("Book1, %sn", $b1->name);
$b2 = new Book;
$b2->name('CPP');
printf("Book2 %sn", $b2->name);
Output?
Book1 C Book2 CPP
is_object( ) function to test whether a value is an object:
if (is_object($x)) { // $x is an object }

3. Special Data types
Resources
A resource is a special variable,
holding a reference to an external resource.
Resources are files,pictures,reasult of query
but except php code..
Database connect function gives you something
by which to identify that connection
when you call the query and close functions
that is called as a resource.
Resources are really integers under the surface.
Their main benefit is that they're garbage collected
when no longer in use.
is_resource( ) function to test whether a value is a resource:
if (is_resource($x)) { // $x is a resource }
$res=database_connect();

3. Special Data types
NULLThere's only one value of the NULL data type.
the case-insensitive keyword NULL.
The NULL value represents a variable that has no value.
$aleph = "beta"; $aleph = null; // variable's value is gone.
is_null( ) function to test whether a value is NULL-for instance,
to see whether a variable has a value:
if (is_null($x)) { // $x is NULL }
Q.PHP does not require explicit variable declaration (T/F) ?
Q.What is type juggling?

Scope of variable :VariableScope
The scope of a variable is the context within which it is defined.
e.g.
$a = 3;
function f( )
{ $a += 2; echo $a;
}
f( );
echo $a;
Output is 2
3
Here variable outside f() and inside f() is different.
Local
Scope

If you want a variable in the global scope to be accessible
from within a function, you can use the global keyword.
Its syntax is: global var1, var2, ...
$a = 3;
function f( )
{ global $a; $a += 2; }
f( );
echo $a;
Output: 5
Include the global keyword in a function before any uses
of the global variable or variables you want to access.
Q.global variables are manipulated by function?(T)
Global
Scope

A static variable retains its value between calls to a function but
is visible only within that function. You declare a variable static
with the static keyword.
<?php
function change_value()
{
static $i=0;
$i++;
echo "Static variable is : $i";
}
$i=10;
change_value();
change_value();
echo "Global Variable is $i”;?>
Static
Scope

Operators
1. Arithmetic Operators:
+, -, *, /, %, -
2. String Concatenation Operator:
. (dot) is used for concatination of String
e.g.
$n = 5;
$s = ‘There are ‘.$n. ‘items’;
3. Autoincrement and Autodecrement Operators:
++ and - -
4. Comparision Operators:
• Equality (==)

Operators
• Identical ( ===)
 If both operands are equal and are of the same data
type then this operator returns true and false
otherwise.
$i = 0;
$f = “0”;
if ($i === $f)
{
echo "they are equal";
}
else
{
echo "they are not equal";
}

Operators
• Bitwise operator
 ~,&,|,^,>>,<<
• Logical operator
 And,or,xor,!
• Assignment opertor =
• Ternary/conditional operator (? :)
• New(object creation)
• Miscellaneous operators-
 Error sppression(@)
To generate or inhibit error
 Execution operator( `…`) backtick
To excute shell cmd in php
Q.@ is used for executing query?T/F

Date & Time function
Date(“format”,$Timestamp)
Ex.
<?php
$t=date(“Y/M/D”);Echo $t;
?>
m-month ex.2
M-mar
D-Fri
d-date ex.21
W-week no.start from 0 (Sunday)
Time :-
$t=time(); //to display current time
Extra Topics to learn from book
•Garbage Collection
•Type casting
•Basic HTML Tags

Flow Control Structures
1. If , if- else ,If- else-if
2. Switch
3. While
4. Do-while
5. For

Flow Control Structures
6. Foreach
7. Declare(directive)
Ex.declare(ticks=2)
8. Exit & return
9. Break & continue
Explanation https://www.tutorialspoint.com

24Monica Deshmane(H.V.Desai College, Pune)
End Of Chapter

Chap1introppt2php(finally done)

Chap1introppt2php(finally done)

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Chap1introppt2php(finally done)