by Subhash Vithanapathirana

Welcome back! Last month's article was all about creating forms and handling/processing the user input using PHP. Assuming it is clear, today we are moving towards the in-built functions of PHP. At the end of the today's article I hope it will open new openings for your imagination since there is no limit to the possibilities of using functions in PHP. So keep focused...

  Introduction

Hopefully you can remember in our September article while we discussed about user defined functions, I mentioned that PHP has a numerous number of in-built or language defined functions. That is what we're about to discussion today. As you already know, function can accept one or more parameters and provide you with a processed result, without having to worry about the internal logic of it. PHP is a function rich language and you will be amazed to find a function for almost any commonly occurring task while you're writing a code. This is one of the reasons for the real power of PHP. These functions make your coding life more enjoyable, less lengthy codes, less time consumption and more readable.

In PHP, there are over 700 functions as per version 5.2 and these can be categorized based on the type of data they work on and what type of tasks they are used for. To name a few; Array functions, Date functions, File system functions, Math functions, String functions etc. My objective of taking PHP in-built functions as the topic is not to explain all the functions in PHP language. It is almost an impossible task which could take ages. Therefore, what I intend is to give you the feel of how to find and use a function whenever you are in a situation to use one. I will be outlining few commonly used functions from above mentioned categories in today's article for you to get an idea.

  Array functions

·   array — Create an array

·   count — Count all elements in an array, or properties in an object

·   sort — Sort an array

·   rsort — Sort an array in reverse order

·   shuffle — Shuffle an array

·   array_sum — Calculate the sum of values in an array

·   array_search — Searches the array for a given value and returns the corresponding key if successful

·   in_array — Checks if a value exists in an array

·   array_keys — Return all the keys of an array

·   array_unique — Removes duplicate values from an array

Examples:

<?php
$myArray = array("Laptop"=>150000,"Mobile Phone"=>43000,"Webcam"=>5000);
$count = count($myArray); // 3
sort($myArray); // sorts the array in ascending order by value
rsort($myArray); // sorts the array in descending order by value
shuffle($myArray); // shuffles the array in random order
$cost = array_sum($myArray); // 198000
$searchKey = array_search(43000, $myArray); // returns the position of 43000 in array
$check = in_array(2000, $myArray); // returns false since 2000 is not found in array
$keys = array_keys($myArray); // returns a new array containing only the keys of $myArray
$uniqueArray = array_unique($myArray); // removes any duplicate values of array
?>

  Date/Time functions

·   date — Format a local time/date

·   time — Return current Unix timestamp

·   strtotime — Parse about any English textual datetime description into a Unix timestamp

·   mktime — Get Unix timestamp for a date

Examples:

<?php
date("Y-m-d"); // returns the current date in given format; 2009-10-18
time(); // returns the current timestamp; 1255840654
strtotime("2009-02-15 16:55:00"); // returns the timestamp of given date (in any format); 1234697100
mktime(0, 0, 0, 12, 32, 1997); // returns the timestamp of given date; 883591200
?>

  File system functions

·   fopen — Opens file or URL

·   fread — Binary-safe file read

·   fwrite — Binary-safe file write

·   filesize — Gets file size

·   filetype — Gets file type

·   fclose — Closes an open file pointer

·   copy — Copies file

·   rename — Renames a file or directory

·   unlink — Deletes a file

Examples:

<?php
$filename = "something.txt";
$size = filesize($filename);
$fp = fopen($filename, "w");
$content = fread($fp, $size);
fclose($fp);

copy($filename, "something_copy.txt");
unlink($filename);
?>

  Math functions

·   max — Find highest value

·   min — Find lowest value

·   pow — Exponential expression

·   sqrt — Square root

·   round — Rounds a float

·   rand — Generate a random integer

·   base_convert — Convert a number between arbitrary bases

Examples:

<?php
$max_val = max(5,42,6,20,5,7,83,2,6,48,9,32); // 82
$min_val = min(5,42,6,20,5,7,83,2,6,48,9,32); // 2
$num = pow(2,8); // 256
$sq = sqrt(16); // 4
$no = round(3.4612,1); // 3.5
$random = rand(0,100); // random number between 0 and 100
$base10 = base_convert(1010111, 2, 10); // 87
?>

  String functions

·   trim — Strip whitespace (or other characters) from the beginning and end of a string

·   strlen — Get string length

·   substr — Return part of a string

·   strtoupper — Make a string uppercase

·   strtolower — Make a string lowercase

·   strpos — Find position of first occurrence of a string

·   str_replace — Replace all occurrences of the search string with the replacement string

·   implode — Join array elements with a string

·   explode — Split a string by string

·   md5 — Calculate the md5 hash of a string

Examples:

It is very important to note that what I explained above is only a handful of functions in PHP. There are lot of resources available in the Web for you to find out the functions and their usage. The official site PHP.net has complete support to all the functions http://php.net/quickref.php

I will be making use of different functions in my next set of articles so that all of you can get familiar with them more in future. Till then, it is recommended for you to try out a few from this list and strengthen your knowledge. Happy coding!

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