Using Arrays in PHP

Sabari · #41 (**permalink**) 08-18-2007, 04:43 AM

array_reduce

array_reduce — Iteratively reduce the array to a single value using a callback function

Example: array_reduce()

<?php
function rsum($v, $w)
{
$v += $w;
return $v;
}

function rmul($v, $w)
{
$v *= $w;
return $v;
}

$a = array(1, 2, 3, 4, 5);
$x = array();
$b = array_reduce($a, "rsum");
$c = array_reduce($a, "rmul", 10);
$d = array_reduce($x, "rsum", 1);
?>

This will result in
$b containing 15,
$c containing 1200 (= 10*1*2*3*4*5),
and $d containing 1.

Sabari · #42 (**permalink**) 08-18-2007, 04:46 AM

array_reverse

array_reverse — Return an array with elements in reverse order

Example: array_reverse()

<?php
$input = array("php", 4.0, array("green", "red"));
$result = array_reverse($input);
$result_keyed = array_reverse($input, true);
?>

This makes both $result and $result_keyed have the same elements, but note the difference between the keys. The printout of $result and $result_keyed will be:

Array
(
[0] => Array
(
[0] => green
[1] => red
)

[1] => 4
[2] => php
)
Array
(
[2] => Array
(
[0] => green
[1] => red
)

[1] => 4
[0] => php
)

Sabari · #43 (**permalink**) 08-18-2007, 04:52 AM

array_shift

array_shift — Shift an element off the beginning of array

Example: array_shift()

<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_shift($stack);
print_r($stack);
?>
This would result in $stack having 3 elements left:

Array
(
[0] => banana
[1] => apple
[2] => raspberry
)
and orange will be assigned to $fruit.

Sabari · #44 (**permalink**) 08-18-2007, 04:54 AM

array_unshift

array_unshift — Prepend one or more elements to the beginning of an array

Example: array_unshift() example

<?php
$queue = array("orange", "banana");
array_unshift($queue, "apple", "raspberry");
print_r($queue);
?>

The above example will output:

Array
(
[0] => apple
[1] => raspberry
[2] => orange
[3] => banana
)

Sabari · #45 (**permalink**) 08-18-2007, 04:55 AM

array_unique

array_unique -- Removes duplicate values from an array

Example array_unique()

$input = array ("a" => "green", "red", "b" => "green", "blue", "red");
$result = array_unique ($input);
print_r($result);

This will output:

Array
(
[b] => green
[1] => blue
[2] => red
)

Sabari · #46 (**permalink**) 08-18-2007, 04:57 AM

array_pad

array_pad -- Pad array to the specified length with a value

Example: array_pad()

$input = array (12, 10, 9);

$result = array_pad ($input, 5, 0);
// result is array (12, 10, 9, 0, 0)

$result = array_pad ($input, -7, -1);
// result is array (-1, -1, -1, -1, 12, 10, 9)

$result = array_pad ($input, 2, "noop");
// not padded

Sabari · #47 (**permalink**) 08-18-2007, 04:58 AM

array_pop

array_pop -- Pop the element off the end of array

Example: array_pop()

$stack = array ("orange", "banana", "apple", "raspberry");
$fruit = array_pop ($stack);

After this, $stack will have only 3 elements:
Array
(
[0] => orange
[1] => banana
[2] => apple
)

and rasberry will be assigned to $fruit.

Sabari · #48 (**permalink**) 08-18-2007, 04:59 AM

array_push

array_push -- Push one or more elements onto the end of array

Example: array_push()

$stack = array ("orange", "banana");
array_push ($stack, "apple", "raspberry");

This example would result in $stack having the following elements:
Array
(
[0] => orange
[1] => banana
[2] => apple
[3] => raspberry
)

Naseema · #49 (**permalink**) 08-18-2007, 06:26 AM

Sabai really great job.....
its very informative .....
keep on dooing this

Sabari · #50 (**permalink**) 08-20-2007, 08:48 AM

array_udiff

array_udiff — Computes the difference of arrays by using a callback function for data comparison

Example: array_udiff()

<?php
class cr {
private $priv_member;
function cr($val)
{
$this->priv_member = $val;
}

function comp_func_cr($a, $b)
{
if ($a->priv_member === $b->priv_member) return 0;
return ($a->priv_member > $b->priv_member)? 1:-1;
}
}
$a = array("0.1" => new cr(9), "0.5" => new cr(12), 0 => new cr(23), 1=> new cr(4), 2 => new cr(-15),);
$b = array("0.2" => new cr(9), "0.5" => new cr(22), 0 => new cr(3), 1=> new cr(4), 2 => new cr(-15),);

$result = array_udiff($a, $b, array("cr", "comp_func_cr"));
print_r($result);
?>

The above example will output:

Array
(
[0.5] => cr Object
(
[priv_member:private] => 12
)

[0] => cr Object
(
[priv_member:private] => 23
)

)

Sabari · #51 (**permalink**) 08-20-2007, 08:50 AM

array_udiff_assoc

array_udiff_assoc — Computes the difference of arrays with additional index check, compares data by a callback function

Example :array_udiff_assoc()

<?php
class cr {
private $priv_member;
function cr($val)
{
$this->priv_member = $val;
}

function comp_func_cr($a, $b)
{
if ($a->priv_member === $b->priv_member) return 0;
return ($a->priv_member > $b->priv_member)? 1:-1;
}
}

$a = array("0.1" => new cr(9), "0.5" => new cr(12), 0 => new cr(23), 1=> new cr(4), 2 => new cr(-15),);
$b = array("0.2" => new cr(9), "0.5" => new cr(22), 0 => new cr(3), 1=> new cr(4), 2 => new cr(-15),);

$result = array_udiff_assoc($a, $b, array("cr", "comp_func_cr"));
print_r($result);
?>

The above example will output:

Array
(
[0.1] => cr Object
(
[priv_member:private] => 9
)

[0.5] => cr Object
(
[priv_member:private] => 12
)

[0] => cr Object
(
[priv_member:private] => 23
)
)

Sabari · #52 (**permalink**) 08-20-2007, 08:53 AM

array_udiff_uassoc

array_udiff_uassoc — Computes the difference of arrays with additional index check, compares data and indexes by a callback function

Example: array_udiff_uassoc()

<?php
class cr {
private $priv_member;
function cr($val)
{
$this->priv_member = $val;
}

function comp_func_cr($a, $b)
{
if ($a->priv_member === $b->priv_member) return 0;
return ($a->priv_member > $b->priv_member)? 1:-1;
}

function comp_func_key($a, $b)
{
if ($a === $b) return 0;
return ($a > $b)? 1:-1;
}
}
$a = array("0.1" => new cr(9), "0.5" => new cr(12), 0 => new cr(23), 1=> new cr(4), 2 => new cr(-15),);
$b = array("0.2" => new cr(9), "0.5" => new cr(22), 0 => new cr(3), 1=> new cr(4), 2 => new cr(-15),);

$result = array_udiff_uassoc($a, $b, array("cr", "comp_func_cr"), array("cr", "comp_func_key"));
print_r($result);
?>

The above example will output:

Array
(
[0.1] => cr Object
(
[priv_member:private] => 9
)

[0.5] => cr Object
(
[priv_member:private] => 12
)

[0] => cr Object
(
[priv_member:private] => 23
)
)

Sabari · #53 (**permalink**) 08-20-2007, 08:54 AM

array_uintersect_assoc

array_uintersect_assoc — Computes the intersection of arrays with additional index check, compares data by a callback function

Example: array_uintersect_assoc()

<?php
$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "GREEN", "B" => "brown", "yellow", "red");

print_r(array_uintersect_assoc($array1, $array2, "strcasecmp"));
?>

The above example will output:

Array
(
[a] => green
)

Sabari · #54 (**permalink**) 08-20-2007, 09:01 AM

array_uintersect_uassoc

array_uintersect_uassoc — Computes the intersection of arrays with additional index check, compares data and indexes by a callback functions

Example: array_uintersect_uassoc()

<?php
$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "GREEN", "B" => "brown", "yellow", "red");

print_r(array_uintersect_uassoc($array1, $array2, "strcasecmp", "strcasecmp"));
?>

The above example will output:

Array
(
[a] => green
[b] => brown
)

Sabari · #55 (**permalink**) 08-20-2007, 09:02 AM

array_uintersect

array_uintersect — Computes the intersection of arrays, compares data by a callback function

Example: array_uintersect()

<?php
$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "GREEN", "B" => "brown", "yellow", "red");

print_r(array_uintersect($array1, $array2, "strcasecmp"));
?>

The above example will output:

Array
(
[a] => green
[b] => brown
[0] => red
)

Sabari · #56 (**permalink**) 08-20-2007, 10:44 PM

Sorting Arrays

Sorting means organizing a bunch of values in alphabetical or numerical order. PHP can be used to sort an array by it's keys or values. The result can keep the corresponding key/value with the original value/key or replace them. That sounds a bit confusing, so here are the examples to sort it out.

Here is a sample array

<?php
$pantry = array(
0 => "tomatoes",
1 => "oranges",
2 => "bananas"
3 => "potatoes",
4 => "bread",
5 => "apples"
);
?>

Use the sort command to sort the values with no regard to the keys. The values only will be changed.

sort($pantry);

The pantry array now looks like this...

0 apples
1 bananas
2 bread
3 oranges
4 potatoes
5 tomatoes

The values have changed places into alphabetical order while the keys remain in the same order.

rsort()

To sort the values in reverse order with no regard to the keys, the rsort command is used.

The pantry array now looks like this...
0 tomatoes
1 potatoes
2 oranges
3 bread
4 bananas
5 apples

The values have changed places into alphabetical order while the keys remain in the same order.

asort()

To sort the values and keep the corresponding keys, the asort command is used.

asort($pantry);

The pantry array now looks like this...

5 apples
2 bananas
4 bread
1 oranges
3 potatoes
0 tomatoes

arsort()

A similar sorting with keys technique can also be done in the reverse order using the arsort command.

arsort($pantry);

The pantry array now looks like this...

0 tomatoes
3 potatoes
1 oranges
4 bread
2 bananas
5 apples

ksort()

To sort the keys and keep the values, the ksort command is used.

ksort($pantry);

The pantry array now looks like this...

0 tomatoes
1 oranges
2 bananas
3 potatoes
4 bread
5 apples

In this case, it remains the same as the original array considering the keys were already in numerical order.

krsort()

To sort the keys and keep the values in reverse order, the krsort command is used.

krsort($pantry);

The pantry array now looks like this...

5 apples
4 bread
3 potatoes
2 bananas
1 oranges
0 tomatoes

shuffle()

The shuffle command is used to randomly reorganize the values of an array. The keys remain the same.

shuffle($pantry);

The pantry array now looks like this...

0 apples
1 potatoes
2 bananas
3 oranges
4 bread
5 tomatoes

raj · #57 (**permalink**) 08-21-2007, 03:09 AM

hi,

how do i get the last value of an array?

Kamalakannan · #58 (**permalink**) 08-21-2007, 03:29 AM

hi raj,

you can use the array_pop() function. This function returns last value of array. If array is empty returns NULL. And original array is end of element is Off.

Eg:

$stack = array("bus", "car", "cycle");
$val = array_pop($stack);

echo $val; // Output : cycle

print_r($stack);
Array(
[0] = 'bus'
[1] = 'car'
)

--R.kamalakannan

Sabari · #59 (**permalink**) 08-21-2007, 03:29 AM

very simple Mr.Raj,

suppose we can take this array
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_pop($stack);
print_r($fruit);

the above print statement will return the last array element, like this

raspberry

raj · #60 (**permalink**) 08-21-2007, 03:29 AM

hi all,

here i have given sample code for delete the array index & their values...

eg:
this loop to delete the empty value of an array

foreach($aResult as $vKey => $Value)
{
//#-- Checking the Value is empty or not
if(is_null($Value)) unset($aResult[$vKey]);
}
//# unset function to destroy the element

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