WORKING WITH PHP ARRAYS
AND FUNCTIONS
Unit - III
1
SYLLABUS
3.1 Array: Types of Array, Arrays definition, Creating
arrays; using arrays() function, using Array identifier,
defining start index value, adding more elements to
array,
3.2 Associative arrays, key-value pair, using for-each
statement to go through individual element with loop.
3.3 Functions: defining a user defined function,
calling function, returning values from function,
Variable scope, Accessing variables with global
statement,
3.4 Setting default values for arguments, passing
with values and passing with reference,
3.5 Working with string, Dates and Time functions,
common mathematical functions.
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3.1 ARRAYS
An array stores multiple values in one single variable.
An array is a special variable, which can hold more
than one value at a time.
If you have a list of items (a list of car names, for
example), storing the cars in single variables could
look like this:
$cars1 = "Volvo";
$cars2 = "BMW";
$cars3 = "Toyota";
However, what if you want to loop through the cars
and find a specific one? And what if you had not 3
cars, but 300?
The solution is to create an array!
An array can hold many values under a single name,
and you can access the values by referring to an index
number.
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3.1.1 CREATING ARRAYS
In PHP, the array() function is used to create an
array:
array( );
In PHP, there are three types of arrays:
Indexed arrays - Arrays with a numeric index
Associative arrays - Arrays with named keys
Multidimensional arrays - Arrays containing one
or more arrays
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3.1.2 USING ARRAY( ) FUNCTION
In PHP, the array() function is used to create an
array:
array( );
Syntax:
$ArrayName = array(value1,value2….valueN);
In Numeric array each elements are assigned a
numeric key value starting from 0 for first elements
and so on.
Example:
<?php
$name=array(“Arpan”, “Soham”, “Helisha”);
print_r($name);
?>
Output:
Array([0] =>Arpan [1] =>Soham [2]=>Helisha)
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3.1.3 USING ARRAY IDENTIFIER
In PHP, we can also create an array using array
identifier.
Syntax:
$ArrayName [ ] = “value”;
Example:
<?php
$name[ ] = “Arpan”;
$name[ ] = “Soham”;
$name[ ] = “Helisha”;
print_r($name);
?>
Output:
Array([0] =>Arpan [1] =>Soham [2]=>Helisha)
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3.1.4 DEFINING START INDEX VALUE
By default starting index of an array is 0.
It is incremented by 1 for each successive
elements of an array.
But it is also possible to define start index of an
array.
Example:
<?php
$name = array(19=> “Arpan”, “Charmi”, “Deep”);
print_r($name);
?>
Output
Array ([19]=> Arpan [20]=>Charmi [21]=>Deep)
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3.1.5 ADDING MORE ELEMENTS TO ARRAY
Once an array id created we can add more elements
to an array using array identifier.
Example:
<?php
$name=array(“Arpan”, “Soham”, “Helisha”);
print_r($name);
echo “<br>”;
$name[ ] = “Shivani”;
print_r($name);
?>
Output:
Array([0] =>Arpan [1] =>Soham [2]=>Helisha)
Array([0] =>Arpan [1] =>Soham [2]=>Helisha [3]=>Shivani)
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3.2 ASSOCIATIVE ARRAYS
In associative array each elements having key
associated with it.
It can be either numeric or string.
Syntax:
$ArrayName = array( Key1=>Value1, Key2=>Value2, …, KeyN=>ValueN)
In PHP, if we don’t specify key value for each element
then it will create a numeric array.
Example (Numeric Key):
<?php
$name = array(19=> “Arpan”, 20=>“Charmi”);
print_r($name);
?>
Output
Array ([19]=> Arpan [20]=>Charmi)
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Example (String Key):
<?php
$marks = array(“JAVA”=> 25, “DWPD”=>30);
print_r($marks);
?>
Output
Array ([JAVA]=> 25 [DWPD]=>30)
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3.3 FUNCTIONS
A function is a block of statements that can be
used repeatedly in a program.
A function will not execute immediately when a
page loads.
A function will be executed by a call to the
function.
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3.3.1 CREATE A USER DEFINED FUNCTION IN
PHP
A user defined function declaration starts with the word
"function“.
Syntax
function functionName()
{
code to be executed;
}
Note: A function name can start with a letter or
underscore (not a number).
Example
<?php
function writeMsg( )
{
echo "Hello world!";
}
writeMsg(); // call the function
?>
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3.3.2 CALLING A FUNCTION
In PHP, function is called using FunctionName
and its argument value.
Syntax:
FunctionName(Argument-Value or Varibale Name);
Example:
<?php
function writeMsg( )
{
echo "Hello world!";
}
writeMsg( ); // call the function
?>
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3.3.3 RETURN A VALUE FROM FUNCTION
In PHP, function can return a single value using
return statement to the point from which the
function is called.
Example
<?php
function sum($x, $y)
{
$z = $x + $y;
return $z;
}
echo "5 + 10 = " . sum(5, 10) . "<br>";
echo "7 + 13 = " . sum(7, 13) . "<br>";
echo "2 + 4 = " . sum(2, 4);
?>
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3.3.4 VARIABLE SCOPE
A variable that is declared inside the function is
called as local variable.
It can be accessed only within the function in which
it is declared.
We can not access the local variables from outside
that function.
A variable that is declared outside all the function
are known as global variable.
But in PHP, to access the global variable inside the
function we need to declare them using global
keyword.
Syntax:
global $variableName;
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Example:
<?php
$mid=15;
$gtu = 45;
$total;
function TotalMarks( )
{
global $mid, $gtu, $total;
$total = $mid + $gtu;
}
TotalMarks( );
echo “Total Marks = $total”;
?>
Output: Total Marks = 60
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3.3.5 DEFAULT ARGUMENTS
In PHP, default argument in function must be assign some
value to the argument while defining it.
Default arguments must be written from right to left direction.
Syntax:
funtion functionName( $argument1, #argument2=Value)
{
Function Body
}
Example
<?php
function total($a, $b = 50)
{
echo “Total = $a + $b<br>";
}
total(350);
total(10,65);
?>
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3.4 CALL BY VALUE
When we pass arguments to the function, the
values of the passed arguments are copied into
argument variables declared inside the argument
list of function definition.
So, called function works with copies of
argument instead of original passed arguments.
So any changes made to these variables in the
body of the function are local to that function and
are not reflected outside it.
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Example
<?php
function addSix($num)
{
$num += 6;
}
$orignum = 10;
addSix( $orignum );
echo "Original Value is $orignum<br />";
?>
Output
Original Value is 10
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3.4.1 CALL BY REFERENCE
It is possible to pass arguments to functions by
reference.
This means that a reference to the variable is
manipulated by the function rather than a copy
of the variable's value.
Any changes made to an argument in these cases
will change the value of the original variable.
You can pass an argument by reference by
adding an ampersand to the variable name in
either the function call or the function definition.
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Example
<?php
function addSix(&$num)
{
$num += 6;
}
$orignum = 10;
addSix( $orignum );
echo "Original Value is $orignum<br />";
?>
Output
Original Value is 16
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3.5 STRING FUNCTIONS
String functions are used to manipulated strings.
chr( )
This function accepts ASCII value as an argument
and returns a character code.
Syntax:
chr(ASCII Value)
Example:
<?php
echo chr(97);
?>
Output
a
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ord( )
This function accepts a string as an argument and
returns the ASCII value of the first character of a
string.
Syntax
ord(string)
Example
<?php
echo ord(“VPMP”);
echo “<br>”;
echo ord(“V”);
?>
Output
86
86
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strtolower( )
This function accepts a string as an argument and
coverts all the characters of the string into lowercase
letters.
Syntax
strtolower(string);
Example
<?php
echo strtolower(“VPMP”);
?>
Output
vpmp
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strtoupper( )
This function accepts a string as an argument and
coverts all the characters of the string into uppercase
letters.
Syntax
strtoupper(string);
Example
<?php
echo strtoupper(“vpmp”);
?>
Output
VPMP
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strlen( )
This function accepts a string as an argument and
returns the number of character of a string.
Syntax
strlen(string)
Example
<?php
echo strlen(“VPMP”);
?>
Output
4
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ltrim( )
This function accepts a string as an argument and
removes white spaces from the left side of the string.
Syntax
ltrim(string)
Example
<?php
echo ltrim(“ VPMP”);
?>
Output
VPMP (Without any leading whitespace)
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rtrim( )
This function accepts a string as an argument and
removes white spaces from the right side of the string.
Syntax
rtrim(string)
Example
<?php
echo rtrim(“VPMP ”);
echo (“ Polytechnic”);
?>
Output
VPMP Polytechnic
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trim( )
This function accepts a string as an argument and
removes white spaces from both side of the string.
Syntax
trim(string)
Example
<?php
echo trim(“VPMP ”);
echo trim(“ Polytechnic”);
?>
Output
VPMPPolytechnic
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substr( )
This function accepts a string as an argument and returns specific
part of the string.
Syntax
substr(string, start [,length])
Start has three values. If it is 0 it means staring from first
character of the string. If it is Positive number then starting from
specified position from beginning of the string. If it is negative
number then staring from specified position from ending of the
string.
Example
<?php
echo substr(“VPMP Polytechnic”,2,6);
echo substr(“VPMP Polytechnic”,2);
echo substr(“VPMP Polytechnic”,-6,2);
?>
Output
PMP Po
PMP Polytechnic
ec
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strcmp( )
This function accepts two string as an argument and compare that
strings. It performs case sensitive comparison.
It returns 0 if the two string are equal.
It returns positive number if string1 is greater than string2.
It returns negative number if string1 is less than string2.
Syntax
strcmp(string1,string2)
Example
<?php
if strcmp(“VPMP”, “vpmp”)
{
echo “Both the string are different”;
}
?>
Output
Both the string are different
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strpos( )
This function accepts two string as an argument and
returns the position of the first occurrence of a search
string inside another string.
It performs case sensitive search.
Syntax
strpos(string1, string2);
Example
<?php
echo strpos(“VPMP Polytechnic”, “Polytech”);
?>
Output
6
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str_replace( )
This function accepts a string as an argument and replaces
specified characters of the sring with another specified
characters.
It returns an integer value indicating number of
replacement occurs in the specified string.
It performs case sensitive replacement operation.
Syntax
str_replace(searchchar, replacechar, string, occurrence);
Example
<?php
echo str_replace(“VPMP”, “LDRP”,”VPMP Polytechnic”);
?>
Output
LDRP Polytechnic
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strrev( )
This function accepts a string as an argument and
reverse that string.
Syntax
strrev(string);
Example
<?php
echo strrev(“VPMP Polytechnic”);
?>
Output
cinhcetyloP PMPV
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3.5.1 MATHEMATICAL FUNCTIONS
Math function are used to perform various
operations on numeric values.
abs( )
This function is used to returns the absolute value of
a number specified as an argument.
Syntax
abs(number);
Example
<?php
echo abs(-10):
echo abs(10):
?>
Output
10
10
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ceil( )
The ceil() function rounds a number UP to the
nearest integer, if necessary.
Syntax
ceil(number);
Example
<?php
echo (ceil(5.1)) ;
?>
Output
6
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floor( )
The floor() function rounds a number DOWN to the
nearest integer, if necessary.
Syntax
floor(number);
Example
<?php
echo (floor(5.1)) ;
?>
Output
5
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round( )
The round() function rounds a floating-point number.
Syntax
round(number, precision);
Number specifies the value to round.
Precision specifies the number of decimal digits to round
to. Default is 0
Example
<?php
echo(round(0.60) “<br>”);
echo(round(0.49) . "<br>");
?>
Output
1
0
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fmod( )
The fmod() function returns the remainder (modulo) of
x/y.
Syntax
fmod(x,y);
x specifies the dividend.
y specifies the divisor.
Example
<?php
$x = 7;
$y = 2;
$result = fmod($x,$y);
echo $result;
?>
Output
1
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max( )
The max() function returns the highest value in an array,
or the highest value of several specified values.
Syntax
max(array_values);
or
max(value1,value2,...);
Example
<?php
echo(max(2,4,6,8,10) . "<br>");
echo(max(array(4,20,8,10)) . "<br>");
?>
Output
10
20
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min( )
The min() function returns the lowest value in an array,
or the highest value of several specified values.
Syntax
min(array_values);
or
min(value1,value2,...);
Example
<?php
echo(min(2,4,6,8,10) . "<br>");
echo(min(array(4,20,8,10)) . "<br>");
?>
Output
2
4
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sqrt( )
The sqrt() function returns the square root of a number.
Syntax
sqrt(number);
Example
<?php
echo(sqrt(1) . "<br>");
echo(sqrt(9) . "<br>");
echo(sqrt(0.64) . "<br>");
echo(sqrt(-9));
?>
Output
1
3
0.8
NAN
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pow( )
The pow() function returns x raised to the power of y.
Syntax
pow(x,y);
x specifies the base to use.
y specifies the exponent.
Example
<?php
echo(pow(2,4) . "<br>");
echo(pow(-2,4) . "<br>");
?>
Output
16
16
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rand( )
The rand() function generates a random integer.
Syntax
rand();
or
rand(min,max);
min specifies the lowest number to be returned. Default is 0.
max specifies the highest number to be returned.
Example
<?php
echo(rand() . "<br>");
echo(rand() . "<br>");
echo(rand(10,100));
?>
Output
7434
7345
14
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DATE AND TIME FUNCTION
The date functions allow you to display, format and
manipulate the date and time on the server.
date( )
The PHP date() function formats a timestamp to a more
readable date and time.
Syntax
date(format,timestamp)
Example
<?php
echo "Today is " . date("Y/m/d") . "<br>";
echo "Today is " . date("Y.m.d") . "<br>";
echo "Today is " . date("Y-m-d") . "<br>";
echo "Today is " . date("l");
?>
Ouput
Today is 2015/08/31
Today is 2015.08.31
Today is 2015-08-31
Today is Monday
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mktime( )
The mktime() function returns the Unix timestamp for a
date.
The Unix timestamp contains the number of seconds
between the Unix Epoch (January 1 1970 00:00:00 GMT)
and the time specified.
Syntax
mktime(hour,minute,second,month,day,year)
Example
<?php
$d=mktime(11, 14, 54, 8, 12, 2014);
echo "Created date is " . date("Y-m-d h:i:sa", $d);
?>
Output
Created date is 2014-08-12 11:14:54am
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time( )
The time() function returns the current time in the
number of seconds since the Unix Epoch (January 1 1970
00:00:00 GMT).
Syntax
time( );
Example
<?php
$t=time();
echo($t . "<br>");
echo(date("Y-m-d",$t));
?>
Output
1440996289
2015-08-31
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checkdate( )
The checkdate() function is used to validate a Gregorian
date.
Syntax
checkdate(month,day,year);
Example
<?php
var_dump(checkdate(12,31,-400));
echo "<br>";
var_dump(checkdate(2,29,2003));
echo "<br>";
var_dump(checkdate(2,29,2004));
?>
Output
bool(false)
bool(false)
bool(true)
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getdate( )
The getdate() function returns date/time information of a
timestamp or the current local date/time.
Syntax
getdate(timestamp);
Example
<?php
print_r(getdate());
?>
Output
Array ( [seconds] => 40 [minutes] => 47 [hours] => 0
[mday] => 31 [wday] => 1 [mon] => 8 [year] => 2015 [yday]
=> 242 [weekday] => Monday [month] => August [0] =>
1440996460 )
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