10 PHP built-in functions you may not know

PHP has a very rich set of built-in functions, many of which we have used, but there are still many functions that most of us are not familiar with, but they are very useful. In this article, I list some little-known PHP functions that will make your eyes bright.

levenshtein()

Have you ever experienced the time when you need to know how different two words are? This function is here to help you solve this problem. It can compare the difference between two strings.

Usage:

<?php
$str1 = "carrot";
$str2 = "carrrott";
echo levenshtein($str1, $str2); //Outputs 2
 
?>

get_defined_vars()

This is a very useful function during debugging. This function returns a multidimensional array containing all defined variables.

Usage:

<?php
print_r(get_defined_vars());
?>

php_check_syntax()

This function is very useful and can be used to check whether the syntax of PHP is correct. For technical reasons, this function has been removed starting with PHP 5.05.

Usage:

<?php
$error_message = "";
$filename = "./php_script.php";
if(!php_check_syntax($filename, &$error_message)) {
   echo "Errors were found in the file $filename: $error_message";
} else {
   echo "The file $filename contained no syntax errors";
}
?>

ignore_user_abort()

This function is used to reject the browser user’s request to terminate the execution of the script. Under normal circumstances, the client's exit will cause the server-side script to stop running.

Usage:

<?php
ignore_user_abort();
?>

highlight_string()

The highlight_string() function is very useful when you want to display PHP code on the page. This function will highlight the PHP code you provide using the color defined by the built-in PHP syntax highlighting. This function has two parameters. The first parameter is a string, indicating that this string needs to be highlighted. If the second parameter is set to TRUE, this function will return the highlighted code as the return value.

Usage

<?php
highlight_string(&#39; <?php phpinfo(); ?>&#39;);
?>

highlight_file

This is a very useful PHP function that returns the specified PHP file and highlights the file content with highlight colors according to syntax and semantics. The highlighted code is processed using HTML markup.

Usage:

<?php
highlight_file("php_script.php");
?>

php_strip_whitespace

This function is also similar to the previous show_source() function, but it will delete comments and spaces in the file.

Usage:

<?php
echo php_strip_whitespace("php_script.php");
?>

get_browser

This function will read the browscap.ini file and return browser compatibility information.

Usage:

<?php
echo $_SERVER[&#39;HTTP_USER_AGENT&#39;];
$browser = get_browser();
print_r($browser);
?>

memory_get_usage(), memory_get_peak_usage(), getrusage()

These functions are used to obtain memory and CPU usage. The memory_get_usage() function returns the memory usage, and the memory_get_peak_usage() function returns the memory. Usage peak, getrusage() returns CUP usage, these functions will give you some useful information when debugging PHP code performance. But please note that these functions are not valid on Windows.

Usage:

<?php
echo "Initial: ".memory_get_usage()." bytes \n";
echo "Peak: ".memory_get_peak_usage()." bytes \n";
$data = getrusage();
echo "User time: ".
    ($data[&#39;ru_utime.tv_sec&#39;] +
    $data[&#39;ru_utime.tv_usec&#39;] / 1000000);
echo "System time: ".
    ($data[&#39;ru_stime.tv_sec&#39;] +
    $data[&#39;ru_stime.tv_usec&#39;] / 1000000);
 
?>

gzcompress(), gzuncompress()

These two functions are used to compress and decompress string data. Their compression rate can reach about 50%. The other functions gzencode() and gzdecode() can achieve similar results, but use different compression algorithms.

Usage:

<?php
$string =
"Lorem ipsum dolor sit amet, consectetur
adipiscing elit. Nunc ut elit id mi ultricies
adipiscing. Nulla facilisi. Praesent pulvinar,
sapien vel feugiat vestibulum, nulla dui pretium orci,
non ultricies elit lacus quis ante. Lorem ipsum dolor
sit amet, consectetur adipiscing elit. Aliquam
pretium ullamcorper urna quis iaculis. Etiam ac massa
sed turpis tempor luctus. Curabitur sed nibh eu elit
mollis congue. Praesent ipsum diam, consectetur vitae
ornare a, aliquam a nunc. In id magna pellentesque
tellus posuere adipiscing. Sed non mi metus, at lacinia
augue. Sed magna nisi, ornare in mollis in, mollis
sed nunc. Etiam at justo in leo congue mollis.
Nullam in neque eget metus hendrerit scelerisque
eu non enim. Ut malesuada lacus eu nulla bibendum
id euismod urna sodales. ";
 
$compressed = gzcompress($string);
$original = gzuncompress($compressed);
 
?>