In this article, Eric will denomonstrate the use of arrays in PHP. This article is mainly for beginner PHP programmers to give them a push in the right direction.
What is an Array?
Arrays can most easilly be described as an ordered list. An array is a list of scalar data (If you don't know what a scalar variable is, you should take a look at my first tutorial. Scalar data in arrays are called 'elements'.) that is 'indexed' (so to speek) with numeric or named keys. A 'key' is either a name or a number given to an element in an array as a reference (if a key is numeric, it is called a 'subscript').
An Example of an Array
<?php $six = 6; $arrayname = array("this is an element",5,$six); echo $arrayname; //prints: this is an element echo $arrayname; //prints: 5 echo $arrayname; //prints: 6 ?>
As you can see, elements in an array can be any type of scalar data (string, integer, double) and can also be other variables. In this example, the 'keys' are numeric (assigned automatically for you), so when echo'ing the elements, you use the array name followed by the subscript ($arrayname[subscript]). Notice that the subscript of the first element is zero? This will always be the case with numeric keys.
Associative arrays are arrays that use named keys that you assign to them. Lets look at a few examples...
<?php $arrayone = array("key1" => "this is the first element.", "key2" => "this is the second element"); $arraytwo = array( "key3" => "this is the first element of the second array", "key4" => "this is the second element of the second array", ); echo $arrayone['key1']; //prints "this is the first element." echo $arraytwo['key3']; //prints "this is the first element of the second array" echo $arrayone['key2']; //prints "this is the second element" echo $arraytwo['key4']; //prints "this is the second element of the second array" ?>
Now we're getting to where you know how to define an array (and an associative array), but you probably don't see how there useful yet. Well think of this, say you have a bakery that sells pies. You have 3 different flavors, and each flavor has a different price. lets make this example in php...
<?php $bakery = array( "cherry" => "5.00", "apple" => "4.00", "other" => "2.00", ); echo "cherry pie costs $bakery['cherry'], apple pie costs $bakery['apple'], and that other pie costs $bakery['other']."; ?>
Ok, you've got an example of how to use arrays (a very basic example, grant me that). But what if you want to give more information on each pie? You now have the cost, but what if you wanted to add the number of pieces you get for that price, and if the pie was sugarless or not? One way is using mutlidimensional arrays.
Think of multidimensional arrays as simply a list of arrays. This might seem confusing at first, but im sure with a few examples (and a few pies) you will get the big picture. Pick up your fork, its time to eat:
<?php $bakery = array( "cherry" => array("5.00","2 pieces","sugar"), "apple" => array("4.00","3 pieces","sugar"), "other" => array("2.00","1 piece","sugar-free"), ); echo "cherry pie costs ".$bakery['cherry'].", and you get ".$bakery['cherry']."."; //prints "cherry pie costs 5.00, and you get 2 pieces." echo "apple pie costs ".$bakery['apple'].", and you get ".$bakery['apple']."."; //prints "apple pie costs 4.00, and you get 3 pieces." echo "the other pie costs ".$bakery['other'].", but its ".$bakery['other']."."; //prints "the other pie costs 2.00, but its sugar-free. ?>
Hopefully now you will be prepared to use arrays when you begin querying mysql databases, and performing other forms of intermediate to advanced data manipulation. If you've noticed, this 'tutorial' wasn't really a tutorial. I'm only trying to give you the basic idea of how to define and use these arrays, not give you all the information a person could possibly fathom. Hey, that might explain the whole "Introduction" word in the title.
array_change_key_case -- Returns an array with all string keys lowercased or uppercased array_chunk -- Split an array into chunks array_count_values -- Counts all the values of an array array_diff_assoc -- Computes the difference of arrays with additional index check array_diff -- Computes the difference of arrays array_fill -- Fill an array with values array_filter -- Filters elements of an array using a callback function array_flip -- Flip all the values of an array array_intersect_assoc -- Computes the intersection of arrays with additional index check array_intersect -- Computes the intersection of arrays array_key_exists -- Checks if the given key or index exists in the array array_keys -- Return all the keys of an array array_map -- Applies the callback to the elements of the given arrays array_merge_recursive -- Merge two or more arrays recursively array_merge -- Merge two or more arrays array_multisort -- Sort multiple or multi-dimensional arrays array_pad -- Pad array to the specified length with a value array_pop -- Pop the element off the end of array array_push -- Push one or more elements onto the end of array array_rand -- Pick one or more random entries out of an array array_reduce -- Iteratively reduce the array to a single value using a callback function array_reverse -- Return an array with elements in reverse order array_search -- Searches the array for a given value and returns the corresponding key if successful array_shift -- Shift an element off the beginning of array array_slice -- Extract a slice of the array array_splice -- Remove a portion of the array and replace it with something else array_sum -- Calculate the sum of values in an array. array_unique -- Removes duplicate values from an array array_unshift -- Prepend one or more elements to the beginning of array array_values -- Return all the values of an array array_walk -- Apply a user function to every member of an array array -- Create an array arsort -- Sort an array in reverse order and maintain index association asort -- Sort an array and maintain index association compact -- Create array containing variables and their values count -- Count elements in a variable current -- Return the current element in an array each -- Return the current key and value pair from an array and advance the array cursor end -- Set the internal pointer of an array to its last element extract -- Import variables into the current symbol table from an array in_array -- Return TRUE if a value exists in an array key -- Fetch a key from an associative array krsort -- Sort an array by key in reverse order ksort -- Sort an array by key list -- Assign variables as if they were an array natcasesort -- Sort an array using a case insensitive "natural order" algorithm natsort -- Sort an array using a "natural order" algorithm next -- Advance the internal array pointer of an array pos -- Get the current element from an array prev -- Rewind the internal array pointer range -- Create an array containing a range of elements reset -- Set the internal pointer of an array to its first element rsort -- Sort an array in reverse order shuffle -- Shuffle an array sizeof -- Get the number of elements in variable sort -- Sort an array uasort -- Sort an array with a user-defined comparison function and maintain index association uksort -- Sort an array by keys using a user-defined comparison function usort -- Sort an array by values using a user-defined comparison function
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