Sometimes you would want to check if a string is an acronym or an abbreviation by testing if it only contains capitalized letters from A to Z and nothing else. There are 2 ways to accomplish this simple task in PHP.

ctype_upper()

Use the native ctype_upper() function and you will know if the provided string contains only uppercase letters:

if (ctype_upper($string)) {
	echo $string.' is all uppercase letters.';
} else {
	echo $string.' is not all uppercase letters.';
}

The Ctype functions would turn out to be very handy when you want to test a string against different character types – digits, alphabetic, alpha-numeric, lowercase letters, uppercase letter, and even punctuations, etc. See the full list here: http://www.php.net/manual/en/ref.ctype.php

strtoupper()

Use the strtoupper() function to transform the string into all uppercase characters that’s capitalized letters, and then compare the transformed string against the original one to see if they are identical. If they are, then you are pretty sure the original string was also a string consisting of ONLY capital letters.

if (strtoupper($string) == $string) {
	echo $string.' is all uppercase letters.';
}

Check if A String Consists of Only Lowercase Letters

The same goes true if you want to do the test other way around. Just use ctype_lower() and strtolower() instead.

Related Posts:

• PHP String Case: Uppercase all Letters or Lowercase all Letters in a String | Uppercase First Letter of a String | Uppercase First Letter of all Words in a String
• PHP Class: Convert Plural to Singular or Vice Versa in English
• PHP: Checking Text Strings against Reserved or Censored Words
• PHP: Change Array Key Case – All Array Keys to Lowercase or Uppercase
• PHP: Create an Array of A Range of Characters (Numbers or Letters) or Multiple Identical Values

While you can somewhat rely on the name extension of a file to determine the mime type, it may not always be accurate. For example, .jpg and .jpeg files are very probably image/jpeg files and .png files are very probably image/png files, but there’s always an exception because file extensions can be faked. To accurately find the mime type of a specific file in PHP, you should use the Fileinfo extension.

Find out if the extension is enabled with the code outlined in the beginning part of the resize image in PHP post.

With the php_fileinfo extension enabled in php.ini, this is the function I come up with:

$finfo = new finfo(FILEINFO_MIME); // return mime type
if ($finfo) {
	$file_name = "/absolute/path/to/some.jpg"; /* Must use absolute path */
	$file_info = $finfo->file($file_name);
	$mime_type = substr($file_info, 0, strpos($file_info, ';'));
	echo $mime_type;
}

Which will get you this:

image/jpeg

The reason it gets complicated in the echo line is that the standard output of FILEINFO_MIME information output by the file() function of the $finfo object is something like this:

image/jpeg; charset=binary

Therefore, you have to literally get everything before the semi-colon to get the mime type information.

If it was a CSS file, the output of the $finfo->file() method would be like this:

text/plain; charset=utf-8

Cool, huh!

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Other than making your 404 error page user friendly, you can redirect it to your index pages such as the homepage, sitemap, or search page, to make it useful for the users. Instead of relying on them to correct the error themselves, you offer the new orientation.

How to redirect a 404 error page to the home page?

There are essentially 3 ways to do this depending on the technology your site is built on.

The .htaccess and HTML solution

This works across all sites that are served by the Apache web server with .htaccess enabled. Add this line in the .htaccess file in the root directory of your domain:

ErrorDocument 404 /404.html

And in 404.html, add a meta tag in the HTML head section:

<meta http-equiv="Refresh" content="1; URL=http://www.example.com/">

So when there’s an 404 Not Found error the user would be first redirected to /404.html and in turn, he or she would be redirected to the homepage http://www.example.com/ (or whatever you change it to) by the meta Refresh actions.

The PHP solution

If you are using PHP to code your site, chances are you know this solution. You can always use the previous solution (The .htaccess and HTML solution) to redirect 404 error page to your home page on a PHP site, but you can also try the pure PHP approach instead.

Whenever a user types in a URL request that you do not recognize, render this:

header("HTTP/1.1 404 Not Found");
header("Location: /");
exit();

Which would redirect the user who has hit a 404 error to the homepage / or any other page URL you specify there.

The WordPress solution

If you are using WordPress for your site, make a 404.php file in your theme directory with the following content:

<?php
header("HTTP/1.1 301 Moved Permanently");
header("Location: ".get_bloginfo('url'));
exit();

WordPress would automatically use 404.php as the default 404 Not Found error page and when a user hits that page, he or she would then be taken to the home page your WordPress blog.

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You can save re-usable data in database such as MySQL so you can load them among different scripts / script sessions, though it may be a bit overwhelming for simple tasks because you have to set up a whole database and the connection credentials, etc.. File system is probably a better approach with regards to storing and retrieving simple tabular data, for not-so-important projects or test projects.

Then should we opt for XML or JSON? XML is bit too formal for teensy jobs. JSON, on the other hand, is the star of simplicity and capable or dealing with both tabular data and objects quite handily.

So we will store tabular data such as an PHP Array to JSON text which would then be stored as a ASCII text file. When we need to use the array again, be it in another PHP script or at a later time, we would just load the JSON string in the file and decode it into an array in PHP.

How can we do this? As simple as abc.

Store PHP Array in File

file_put_contents('array.txt', json_encode($your_array));

Read Array from File

$your_array = json_decode(file_get_contents('array.txt'), true);

Serialize()

Another approach is to use the serialize() and unserialize() functions of PHP. You may want to read this to choose between them: http://stackoverflow.com/questions/804045/preferred-method-to-store-php-arrays-json-encode-vs-serialize

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Provided that your user account on the server has the privileges to access crontab thus can create or remove cron jobs, you can use this PHP class to integrate crontab in your application. I created it for many of my own projects that need crontab to do scheduled jobs. It’s pretty straightforward.

Don’t know what crontab is and how it works? Read here and here. With this class, you or your users can easily set up crontab jobs and automate tasks by schedule with the web interface.

The Crontab Class

class Crontab {

	// In this class, array instead of string would be the standard input / output format.

	// Legacy way to add a job:
	// $output = shell_exec('(crontab -l; echo "'.$job.'") | crontab -');

	static private function stringToArray($jobs = '') {
		$array = explode("\r\n", trim($jobs)); // trim() gets rid of the last \r\n
		foreach ($array as $key => $item) {
			if ($item == '') {
				unset($array[$key]);
			}
		}
		return $array;
	}

	static private function arrayToString($jobs = array()) {
		$string = implode("\r\n", $jobs);
		return $string;
	}

	static public function getJobs() {
		$output = shell_exec('crontab -l');
		return self::stringToArray($output);
	}

	static public function saveJobs($jobs = array()) {
		$output = shell_exec('echo "'.self::arrayToString($jobs).'" | crontab -');
		return $output;
	}

	static public function doesJobExist($job = '') {
		$jobs = self::getJobs();
		if (in_array($job, $jobs)) {
			return true;
		} else {
			return false;
		}
	}

	static public function addJob($job = '') {
		if (self::doesJobExist($job)) {
			return false;
		} else {
			$jobs = self::getJobs();
			$jobs[] = $job;
			return self::saveJobs($jobs);
		}
	}

	static public function removeJob($job = '') {
		if (self::doesJobExist($job)) {
			$jobs = self::getJobs();
			unset($jobs[array_search($job, $jobs)]);
			return self::saveJobs($jobs);
		} else {
			return false;
		}
	}

}

Public Methods

You may well ignore the private methods that do the internal chores. And keep in mind that any cron job is a text string.

1. getJobs() – returns an array of existing / current cron jobs. Each array item is a string (cron job).
2. saveJobs($jobs = array()) – save the $jobs array of cron jobs into the crontab so they would be run by the server. All existing jobs in crontab are erased and replaced by $jobs.
3. doesJobExist($job = ”) – check if a specific job exist in crontab.
4. addJob($job = ”) – add a cron job to the crontab.
5. removeJob($job = ”) – remove a cron job from crontab.

This class has been tested on Rackspace Cloud and Wiredtree. Feel free to post your comments below and let me know how it works on other web hosts.

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• PHP: Email Attachment Class
• PHP: Differences between exec(), shell_exec(), system() and passthru()
• PHP: Resize Image and Store to File
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• PHP: File Upload Script (HTML Form + PHP Handler Class)

I coded a lot in Zend Studio 5.5.1, the gold old version that’s insanely popular because it made it so easy to code in PHP. As PHP evolves, ZS 5.5.1 gradually falls behind of the edge and it simply becomes imperative that you switch to the latest version of Zend Studio, the 8.

The IDE is built on Eclipse, which I have never used before. It’s great but one still needs some time to learn the curves before he or she can jump in and swim like a whale. Today I gave it a test drive and have some tips to share with you when you are just starting out with Zend Studio 8.

1. Change Default Character Encoding

Before you create your project or editing any existing PHP files, you may need to change the default encoding of the Zend Studio Workspace, or make sure it is what you usually work in.

By default, the encoding is that of the container (your operating system). I’m using a Chinese Windows 7 so the default encoding is GBK and it is everything but good because I primarily develop English projects.

For North America users, the default encoding should be ISO-8859-1. If you open up a file that’s encoded in UTF8 without changing the encoding accordingly, you may end up screwing up the file. And another victim.

To change the default encoding of Zend Studio: Windows –> Preferences –> General –> Workspace –> Text file encoding, switch to “Other” and select the encoding you normally use.

2. Display Function Parameters Hint on Demand

In 5.5.1, function parameters hint is automatically displayed when you place the cursor in the parentheses. However in 8, the hint is only automatically shown after you immediately finish typing the function name. When the focus moves away or you click anywhere else in the window, the hint disappears and if you don’t know the correct shortcut keys, you wouldn’t be able to get it back.

After a few searches, I found out the key combinations to get the parameters hint re-appear: Alt + Shift + /

Some pages say it’s Ctrl + Shift + Space but it didn’t work out for me. Maybe it’s a version thing?

3. Display Potential Function Candidates / Auto-complete Function Names

Along with the previous tip, this one is pretty important in modern IDE because they are essential in boosting one’s coding productivity. Can’t live without them.

When you are typing the function name, Zend Studio would guess what you mean and display a list of possible candidates for you to choose from.

If you want it to appear again, just place the cursor on the function name and use Alt + / to make Zend Studio makes a guess again.

4. Display All Shortcut Key Combinations

You can use a lot of shortcut keys in Zend Studio 8 to make things happen quickly and intuitively, just press Ctrl + Shift + L to bring up the key map to see the full list. Here’s a list of the commonly used commands:

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Given a directory, how to display the contents (directories and files under it) of it recursively and exhaustively? Here’s the code:

$dir = '/path/to/directory'; // without trailing slash, can be absolute paths such as '/home/jim/public_html' or relative paths such as 'samples'

getDirContents($dir);

function getDirContents($dir) {
	if (is_dir($dir)) {
		$dirs = explode('/', $dir);
		$last_dir = $dirs[count($dirs) - 1];
		echo '<strong>'.$last_dir.'</strong>';
	    if ($dh = opendir($dir)) {
	    	echo '<ul>';
	        while (($file = readdir($dh)) !== false) {
	        	if ($file == '.' || $file == '..') {} else {
		        	echo '<li>';
		        	if (is_dir($dir.'/'.$file)) {
		        		getDirContents($dir.'/'.$file);
		        	} else {
		        		echo $file;
		        	}
		        	echo '</li>';
	        	}
	        }
	        echo '</ul>';
	        closedir($dh);
	    }
	}
	return false;
}

Recursively, the function getDirContents() explores every entry in the directory. If the entry is a file, it simply prints it; if it is a directory, it opens another subroutine of itself to explore that directory; and so forth, until every branch and sub-branches, etc. are all printed out.

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One of my old Internet friends Brad made a very nice online slide that introduces to you some of the exciting new features of PHP 5.3. I’m most interested in namespace that would make coding in a large project and code reuse much easier, especially for people who find keeping naming conventions a challenge in the team.

Here’s the original post and slide: http://bradley-holt.com/2010/11/new-features-in-php-53/

All the new stuff and concepts are presented in a practical manner that’s extremely straightforward. Programmers should find them a breeze to crunch.

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Linux timestamp is a number of seconds from the Epoch of Linux, large number of seconds. When you are counting the time interval between 2 times or 2 dates, the result is usually in seconds as well. Understandably, it’s everything but user friendly to just present the number of seconds to the users, e.g. 153297 s since last visit.

To display the time interval in a human readable format instead of in seconds, you can use the following function:

function getHumanTime($s) {
	$m = $s / 60;
	$h = $s / 3600;
	$d = $s / 86400;
	if ($m > 1) {
		if ($h > 1) {
			if ($d > 1) {
				return (int)$d.' d';
			} else {
				return (int)$h.' h';
			}
		} else {
			return (int)$m.' m';
		}
	} else {
		return (int)$s.' s';
	}
}

This is what I used for Usable Databases to display length of time since the user’s last visit to a certain page. d indicates day, h hour, m minute and s seconds. This function requires a number of seconds as input and convert it into human readable time periods such as x hours or x days.

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Often we need the users to enter a valid string of date or time in the form. But how do you validate the strings with regular expressions? In PHP, you can use these functions and regular expressions.

RegExp and function to validate against date string:

// Default: YYYY-MM-DD
function isDate($subject, $separator = '-') {
	return preg_match('@^\d{4}'.$separator.'(0[1-9]|1[0-2])'.$separator.'(0[1-9]|1[0-9]|2[0-9]|3[0-1])$@', $subject);
}

RegExp and function to validate against time string:

// Default: HH:MM:SS
function isTime($subject, $separator = ':') {
	return preg_match('@^(0[1-9]|1[0-9]|2[0-4])'.$separator.'(0[1-9]|[1-5][0-9])'.$separator.'(0[1-9]|[1-5][0-9])$@', $subject);
}

If you need to validate against a different format, just change the $separator.

Now that you have the functions to validate date and time, you can combine them to verify date time strings such as 2016-04-30 18:19:05:

function isDateTime($subject) {
	$subject_array = explode(' ', $subject);
	if (count($subject_array) == 2) {
		return isDate($subject_array[0]) && :isTime($subject_array[1]) || $subject == '0000-00-00 00:00:00';
	}
	return false;
}

At Form Kid, these are functions I use for fields that need validation of the date and time.

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When I’m developing the online form creator that enables the users to create form fields that accept only certain type of numbers, I need to verify if a given string is a valid natural number such as 1, 2, 3, 4, …. I’m writing the code / functions in PHP but you can literally use the regular expression in other programming languages as well. I use the following function to distinguish strings if they are natural numbers or positive integers.

function isNaturalNumber($subject) {
	return preg_match('|^[1-9][0-9]*$|', $subject);
}

You can add for a leading plus sign as well:

^+?[1-9][0-9]*$

Regular Expression for Negative Integers?

Negative integers are –1, –2, –3, …. Just add a minus sign before the regular expression for positive integers:

^-[1-9][0-9]*$

Regular Expression for Non-negative Integers?

That is, 0, 1, 2, 3, 4, …. By a little help of the isNaturalNumber function, you can use this function to check if a string is a legal non-negative integer:

function isNonNegativeInteger($subject) {
	// @^(0|[1-9][0-9]*)$@
	if ($subject == '0' || isNaturalNumber($subject)) {
		return true;
	}
}

Or if you insist on using a regular expression:

function isNonNegativeInteger($subject) {
	return preg_match('@^(0|[1-9][0-9]*)$@', $subject);
}

PHP functions to check if a string is a valid integer?

Just use the above functions in combination or the native is_integer() function of PHP.

function isInteger() {
	return isNegativeInteger($subject) || isNonNegativeInteger($subject);
}

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The strange thing is that the native empty() function of PHP treats a string of ‘0’ as empty:

$str = '0';
echo empty($str) ? 'empty' : 'non-empty';

And it will output ‘empty’. Therefore if you need to examine if a string is truly an empty string with zero length, you have to use:

echo strlen($str) == 0 ? 'empty' : 'non-empty';

Or you can use this function:

function isNonEmpty($subject) {
	return !empty($subject) || is_numeric($subject);
}

Which checks if the input string $subject is a numeric value (which makes it non-empty) or if it’s non-empty with empty() function when it’s not a numeric value.

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I created a free online web form builder a while back and since it went well in search engine rankings, spammers and phishers found it and started to use it creating forms to collect email account usernames and passwords through phishing attempts. I’ve got to do something before my host closes down my site because of all the complaints and alerts from security department of the universities. They’ve got good reasons. I’m hosting all the phishing forms.

Phishers tend to use URL slugs that include words such as ‘admin’, ‘webmail’ or ‘account’ so that the form seems authoritative at first glance. After they have signed up, they will create forms with fields labeled ‘Password’ or something. So what I’m going to do is to list all such words as reserved words and prohibit the users from doing anything with them.

A function will be needed to examine a subject string against an array of reserved words that will be censored when users use them as input. Listed is a my function:

public static function isStringLegal($subjectString = '', $disallowedWords = array()) {
	$alphabetSubject = preg_replace('|[^a-zA-Z]+|', '', $subjectString);
	foreach ($disallowedWords as $disallowedWord) {
		if (stripos($alphabetSubject, $disallowedWord) !== false) {
			return false;
		}
	}
	return true;
}

The PHP function stripos() returns a numeric value if it finds $disallowedWord in $alphabetSubject, case-insensitive. If it fails to find anything, it returns false.

A sample disallowed words list:

$slugDisallowedWords = array(
	'formkid',
	'kavoir',
	'mail',
	'admin',
	'account',
	'password'
);

The disallowed words list can only contain alphabet letters. If you need a phrase such as ‘no way’, you have to add it in the array as ‘noway’. This is to prevent illegal attempts to add any word or phrase in manners such as ‘a-d-m-i-n’ or ‘Pa_ss Word’. All the non-alphabet letters / characters are first gotten rid of and then the deprived string which contains only alphabet letters are checked against each word in the disallowed words list.

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The easy way to add a username and password pair in the .htpasswd file is to use an online password generator tool that converts the clear text password into its hash, a.k.a. the encrypted password. The problem with this approach is that you have to manually create the pair and append it to .htpasswd. Is there a way to dynamically generate encrypted passwords for .htpasswd in PHP?

According to http://httpd.apache.org/docs/2.2/misc/password_encryptions.html, we have come up with the following solution:

$pass = 'YourClearTextPasswordString';
$hash = base64_encode(sha1($pass, true));
$encoded = '{SHA}'.$hash;
echo $encoded;

And $encoded is the result we need, which would look something like:

{SHA}hNz9UE9WLiMlzYI+LRtwr0U+DHY=

Suppose the username is ‘manager’ and you can add the following line at the end of your .htpasswd file to make the credentials in effect:

manager:{SHA}hNz9UE9WLiMlzYI+LRtwr0U+DHY=

You can also write / append this to the file by PHP but that’s not covered here.

What’s better, the SHA1 algorithm is much more advanced than DES which most of the online .htpasswd generation tool still uses to generate the hash string of the clear password for you. DES supports only 8 digits and that’s where lengthy passwords fail.

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Depending on the web server software you use, your PHP script will be consuming significantly different amount of memory (RAM). If you are using Apache without proper optimization, the simplest request that does nothing but returns a status code will need 150kB of memory. Multiply this by 2000 visits per day and by 10 sites in a single Linux VPS box, you will have some serious OOM (Out Of Memory) problems.

However if you are using simplistic web server software such as Lighttpd, the situation will get a lot better. But you would still like some improvements to your PHP script itself. So does one first know how much memory a PHP script consumes at run time?

The answer is the memory_get_peak_usage() function. At the end of your PHP script (footer script for a PHP site, you get the idea), put this line:

echo memory_get_peak_usage();

Or you can write the data down in a text file:

file_put_contents('mu.txt', memory_get_peak_usage());

The output is in bytes. Better yet, you can record down the URL request, HTTP request type and memory usage in the mu.txt file so that you can examine it regularly to make adjustments to your server and PHP scripts:

$mu = fopen('mu.txt', 'a');
fwrite($mu, $_SERVER['REQUEST_URI'].', '.$_SERVER['REQUEST_METHOD'].', '.memory_get_peak_usage()."\n");

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