Array String - Web Programming

LEARNING OUTCOMES :
Define array
Describe types of array
Modify Array Elements
Loop in Array
Define String
String Function

ARRAY
v  Array is a data structure that stores one or more similar type of values in a single
value.
v  For example if you want to store 100 numbers then instead of defining 100
variables its easy to define an array of 100 length.
v  There are three different kind of arrays and each array value is accessed using an
ID which is called array index.

TYPES OF ARRAY
v  Types of array are as follows :
a)  Numeric array - An array with a numeric index. Values are stored and accessed in
linear fashion
b)  Associative array - An array with strings as index. This stores element values in
association with key values rather than in a strict linear index order.
c)  Multidimensional array - An array containing one or more arrays and values are
accessed using multiple indices

NUMERIC ARRAY
v  These arrays can store numbers, strings and any object but their index will be
prepresented by numbers. By default array index starts from zero.
v  A numeric array stores each array element with a numeric index.
v  Example
Following is the example showing how to create and access numeric arrays.
Here we have used array() function to create array. This function is explained in
function reference.

<?php
/* First method to create array. */
$numbers = array( 1, 2, 3, 4, 5);
foreach( $numbers as $value )
{
echo "Value is $value ";
}
?>
<?php
/* Second method to create array. */
$numbers[0] = "one";
$numbers[1] = "two";
$numbers[2] = "three";
$numbers[3] = "four";
$numbers[4] = "five";
foreach( $numbers as $value )
{
echo "Value is $value ";
}
?>
EXAMPLE

Value is 1
Value is 2
Value is 3
Value is 4
Value is 5
Value is one
Value is two
Value is three
Value is four
Value is five
OUTPUT
OR

Associative Arrays
v  The associative arrays are very similar to numeric arrays in term of functionality
but they are different in terms of their index.
v  Associative array will have their index as string so that you can establish a strong
association between key and values.
v  To store the salaries of employees in an array, a numerically indexed array would
not be the best choice. Instead, we could use the employees names as the keys
in our associative array, and the value would be their respective salary.
v  ID key is associated with a value.
v  Storing data about specific named values
NOTE: Don't keep associative array inside double quote while printing otheriwse it
would not return any value.

<?php
/* First method to associate create array. */
$salaries = array("mohammad" => 2000, "qadir" => 1000, "zara" => 500);
echo "Salary of mohammad is ". $salaries['mohammad'] . " ";
echo "Salary of qadir is ". $salaries['qadir']. " ";
echo "Salary of zara is ". $salaries['zara']. " ";
?>
EXAMPLE

<?php
/* Second method to create array. */
$salaries['mohammad'] = "high";
$salaries['qadir'] = "medium";
$salaries['zara'] = "low";
echo "Salary of mohammad is ". $salaries['mohammad'] . " ";
echo "Salary of qadir is ". $salaries['qadir']. " ";
echo "Salary of zara is ". $salaries['zara']. " ";
?>
EXAMPLE
ID KEY

Salary of mohammad is 2000
Salary of qadir is 1000
Salary of zara is 500
Salary of mohammad is high
Salary of qadir is medium
Salary of zara is low
OUTPUT

Multidimensional Arrays
v  A multi-dimensional array each element in the main array can also be an array.
And each element in the sub-array can be an array, and so on. Values in the multi-
dimensional array are accessed using multiple index.
v  Array of array
v  Example
In this example we create a two dimensional array to store marks of three
students in three subjects:
This example is an associative array, you can create numeric array in the same
fashion.

<?php
$marks = array("mohammad" => array("physics" => 35, "maths" => 30, "chemistry" => 39),
"qadir" => array("physics" => 30,"maths" => 32, "chemistry”=> 29),
"zara" => array("physics" => 31,"maths" => 22,"chemistry" => 39));
/* Accessing multi-dimensional array values */
echo "Marks for mohammad in physics : " ;
echo $marks['mohammad']['physics'] . " ";
echo "Marks for qadir in maths : ";
echo $marks['qadir']['maths'] . " ";
echo "Marks for zara in chemistry : " ;
echo $marks['zara']['chemistry'] . " ";
?>
Example 1

OUTPUT
Marks for mohammad in physics : 35
Marks for qadir in maths : 32
Marks for zara in chemistry : 39

MODIFY ARRAY ELEMENTS
v  Array functions allow to manipulate arrays. PHP function (built in) for array :
a)  array() – create array
b)  array_count_values()
c)  array_combine()
d)  array_intersect()
e)  array_diff()
f)  array_sum()
g)  in_array()
www.w3schools.com/php/php_ref_array.asp

Loop function in array
v  Foreach Loop : Example 1 (Automatic)

Loop function in array
v  Foreach Loop : Example 2 (Specific ID)

EXERCISE
QUESTION
<?php
$cars=array("Volvo”,BMW","Toyota", “Audi”);
$arrlength=count($cars);
for($x=0;$x<$arrlength;$x++)
{
echo $cars[$x];
}
?>

EXERCISE
OUTPUT 1
Volvo, BMW, Toyota, Audi

STRING
v The string functions allow you to manipulate
strings.
v A string variable is used to store and manipulate
text.
v String variables are used for values that contain
characters.

STRLEN() FUNCTION
The strlen() function returns the length of a string.
DEFINITION & USAGE
strlen(string)
SYNTAX

STRLEN() FUNCTION
Parameter Description
string Required. Specifies the string to
check

strlen() function
12
OUTPUT
<?php
echo strlen("Hello world!");
?>
EXAMPLE

strpos() function
q The strpos() function finds the position of the last occurrence of a string
inside another string.
q This function returns the position on success, otherwise it returns
FALSE.
DEFINITION & USAGE
strpos(string,find,start)
SYNTAX

strpos() function
string Required. Specifies the string to search
find Required. Specifies the string to find
start Optional. Specifies where to begin the search

strpos() function
<?php
echo strpos("Hello world!","world");
?>
EXAMPLE
6
OUTPUT

strpos() function
NOTE
The position of the string "world" in the example
above is 6. The reason that it is 6 (and not 7), is
that the first character position in the string is 0,
and not 1.

strstr() function
q  The strstr() function searches for the first occurrence of a string
inside another string.
q  This function returns the rest of the string (from the matching point),
or FALSE, if the string to search for is not found.
DEFINITION & USAGE
strstr(string,search)
SYNTAX

strstr() function
string Required. Specifies the string to search
search Required. Specifies the string to search for. If this
parameter is a number, it will search for the
character matching the ASCII value of the number

strstr() function
<?php
echo strstr("Hello world!","world");
?>
EXAMPLE 1
world!
OUTPUT

substr() function
The substr() function returns a part of a
string.
DEFINITION & USAGE
substr(string,start,optional_length)
SYNTAX

substr() function
string Required. Specifies the string to return a part of
start • Required. Specifies where to start in the string. A positive number - Start at
a
specified position in the string
• A negative number - Start at a specified position from the end of the string
• 0 - Start at the first character in string
length • Optional. Specifies the length of the returned string. Default is to the end of
the string. A positive number - The length to be returned from the start
parameter
• Negative number - The length to be returned from the end of the string

substr() function
<?php
echo substr("Hello world!",6);
?>
EXAMPLE 1
world!
OUTPUT

substr() function
<?php
echo substr("Hello world!",6,5);
?>
EXAMPLE 2
world
OUTPUT

EXERCISE
<?php
echo strpos("My Unexpected
String!","ex");
?>
QUESTION 1

EXERCISE
<?php
echo substr('abcdefghijk', 1);
?>
QUESTION 2

EXERCISE
QUESTION 3
<?php
echo strlen(“welcome back!");
?>

EXERCISE
QUESTION 4
<?php
echo strstr(“welcome back",“wel");
?>

EXERCISE
OUTPUT 4
welcome back

Array String - Web Programming

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