Arrays in PHP

What are Arrays in PHP ?

In PHP array is the collection of elements with common identifiers (identifiers are used to name variables, functions, constants, and classes),can have different Datatypes  and continuous in memory .

Important points Related to Array in PHP 

  • To declare array ,array function is used $array[].
  • In array subscript starts with ‘Zero'(0).
  • In PHP Array can be declared without element.
  • Array in PHP  support interpolation.
  • Array in PHP   are using dynamic memory allocation ie they are resized automatically as element are assigned or added to array

Types Of Array:

How to define array in php?

$collect=array(‘red’,’yellow’,’123′,false);

In above line $collect is array variable ,array is syntax of array function and red , yellow ,123,false are  the element of array.

there are other ways to declare array in PHP

for example

$collection[]=’city’;

$collection[]=’phone’;

$collection[]=’dob’;

 in above example we are adding element in array  $collection[] simply adding the value in array variable.

we also add element in array thru Index like

$collection[3]=’sport’;

$collection[4]=’school’;

these type of array called Indexed arrays these different method are used according to requirement .

To find out length of an array or number of element in array we can use count() function .

eg. count ($collection);

output will be 5 since we are added 5 element in array form 0-city to 4-school.

 

How to display or use the value of an array

  • print_r($collection); function is use to print formatted output of an array.
  • another method is to use for loop to use an array eg.

for($i=0;i<$n; $i++)

{

echo”Element at i Index is $collection[$i]”;

}

Useful Function of array in PHP

  • shuffle array
  • sort array
  • slice array
  • merge array

Shuffle array :   This function is use to shuffle or  randomizes the order of the elements in an array.

Syntax: shuffle($array_name);

Sort array : This function sort arrays in ascending order, To  sort arrays in descending order we use  rsort()

Syntax: sort($array_name)rsort($array_name)

Other sort function

  • asort() – sort associative arrays in ascending order, according to the value
  • ksort() – sort associative arrays in ascending order, according to the key
  • arsort() – sort associative arrays in descending order, according to the value
  • krsort() – sort associative arrays in descending order, according to the key

Slice array :if you wanted some element from an array then you can use slice function

$array = array_slice($array, 0, 2);

The second parameter is the start point ( 0 means to start from the beginning of the array).

The third parameter is the length of the resulting array

Merge array: To merge to array wen can use array_merge() function

$array = array_merge ($array1,$array2);

the above will result an array consisting element of both the array.

Array Function syantax

Description of function

array() Creates an array
array_change_key_case() Changes all keys in an array to lowercase or uppercase
array_chunk() Splits an array into chunks of arrays
array_column() Returns the values from a single column in the input array
array_combine() Creates an array by using the elements from one “keys” array and one “values” array
array_count_values() Counts all the values of an array
array_diff() Compare arrays, and returns the differences (compare values only)
array_diff_assoc() Compare arrays, and returns the differences (compare keys and values)
array_diff_key() Compare arrays, and returns the differences (compare keys only)
array_diff_uassoc() Compare arrays, and returns the differences (compare keys and values, using a user-defined key comparison function)
array_diff_ukey() Compare arrays, and returns the differences (compare keys only, using a user-defined key comparison function)
array_fill() Fills an array with values
array_fill_keys() Fills an array with values, specifying keys
array_filter() Filters the values of an array using a callback function
>array_flip() Flips/Exchanges all keys with their associated values in an array
array_intersect() Compare arrays, and returns the matches (compare values only)
array_intersect_assoc() Compare arrays and returns the matches (compare keys and values)
array_intersect_key() Compare arrays, and returns the matches (compare keys only)
array_intersect_uassoc() Compare arrays, and returns the matches (compare keys and values, using a user-defined key comparison function)
array_intersect_ukey() Compare arrays, and returns the matches (compare keys only, using a user-defined key comparison function)
array_key_exists() Checks if the specified key exists in the array
array_keys() Returns all the keys of an array
array_map() Sends each value of an array to a user-made function, which returns new values
array_merge() Merges one or more arrays into one array
array_merge_recursive() Merges one or more arrays into one array recursively
array_multisort() Sorts multiple or multi-dimensional arrays
array_pad() Inserts a specified number of items, with a specified value, to an array
array_pop() Deletes the last element of an array
array_product() Calculates the product of the values in an array
array_push() Inserts one or more elements to the end of an array
array_rand() Returns one or more random keys from an array
array_reduce() Returns an array as a string, using a user-defined function
array_replace() Replaces the values of the first array with the values from following arrays
array_replace_recursive() Replaces the values of the first array with the values from following arrays recursively
array_reverse() Returns an array in the reverse order
array_search() Searches an array for a given value and returns the key
array_shift() Removes the first element from an array, and returns the value of the removed element
array_slice() Returns selected parts of an array
array_splice() Removes and replaces specified elements of an array
>array_sum() Returns the sum of the values in an array
array_udiff() Compare arrays, and returns the differences (compare values only, using a user-defined key comparison function)
>array_udiff_assoc() Compare arrays, and returns the differences (compare keys and values, using a built-in function to compare the keys and a user-defined function to compare the values)
array_udiff_uassoc() Compare arrays, and returns the differences (compare keys and values, using two user-defined key comparison functions)
array_uintersect() Compare arrays, and returns the matches (compare values only, using a user-defined key comparison function)
array_uintersect_assoc() Compare arrays, and returns the matches (compare keys and values, using a built-in function to compare the keys and a user-defined function to compare the values)
array_uintersect_uassoc() Compare arrays, and returns the matches (compare keys and values, using two user-defined key comparison functions)
array_unique() Removes duplicate values from an array
array_unshift() Adds one or more elements to the beginning of an array
array_values() Returns all the values of an array
array_walk() Applies a user function to every member of an array
array_walk_recursive() Applies a user function recursively to every member of an array
arsort() Sorts an associative array in descending order, according to the value
asort() Sorts an associative array in ascending order, according to the value
compact() Create array containing variables and their values
count() Returns the number of elements in an array
current() Returns the current element in an array
each() Returns the current key and value pair from an array
end() Sets the internal pointer of an array to its last element
extract() Imports variables into the current symbol table from an array
in_array() Checks if a specified value exists in an array
key() Fetches a key from an array
krsort() Sorts an associative array in descending order, according to the key
ksort() Sorts an associative array in ascending order, according to the key
list() Assigns variables as if they were an array
Sorts an array using a case insensitive “natural order” algorithm
natsort() Sorts an array using a “natural order” algorithm
next() Advance the internal array pointer of an array
pos() Alias of current()
prev() Rewinds the internal array pointer
range() Creates an array containing a range of elements
reset() Sets the internal pointer of an array to its first element
rsort() Sorts an indexed array in descending order
shuffle() Shuffles an array
sizeof() Alias of count()
sort() Sorts an indexed array in ascending order
uasort() Sorts an array by values using a user-defined comparison function
uksort() Sorts an array by keys using a user-defined comparison function
usort() Sorts an array using a user-defined comparison function

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