A collection of useful but little known functions in PHP

This article summarizes the useful but little-known functions in PHP with examples. Share it for your reference, as follows:

PHP has a wealth of built-in functions, many of which we have used, but there are still many functions that most of us are unfamiliar with, but they are 10 points useful. In this article, I've listed one little-known PHP function that will make your eyes shine.

levenshtein()

Have you ever needed to know how different two words are? This function is to help you solve this problem. It can compare the different degrees of two strings.

Usage:

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

get_defined_vars()

This is a very useful function when debugging debug. This function returns a multidimensional array containing all the defined variables.

Usage:

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, starting with PHP 5.05, this function has been removed.

Usage:

$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 deny the browser-side user's request to terminate script execution. Under normal circumstances, the exit of the client will cause the server-side script to stop running.

Usage:

ignore_user_abort();

highlight_string()

The highlight_string () function is useful when you want to display the PHP code on the page. This function will highlight the PHP code you provided with the color defined by the built-in PHP syntax highlight. This function takes two arguments. The first argument is a string, indicating that the string needs to be highlighted. If the second parameter is set to TRUE, the function returns the highlighted code as a return value.

Usage:

highlight_string('<?php phpinfo(); ?>');

highlight_file

This is a very useful PHP function, it can return the specified PHP file, and according to the syntax semantics with highlighting the file content. The highlighted code is processed with HTML tags.

Usage:

highlight_file("php_script.php");

php_strip_whitespace

This function is similar to the previous show_source () function, but it removes comments and spaces from the file.

Usage:

echo php_strip_whitespace("php_script.php");

ge
owser

This function reads the browscap. ini file and returns browser compatibility information.

Usage:

echo $_SERVER['HTTP_USER_AGENT'];
$browser = get_browser();
print_r($browser);

memory_get_usage(),memory_ge

ak_usage(),getrusage()

These functions are used to get memory and CPU usage. The memory_get_usage () function returns memory usage, the memory_ge

ak_usage () function returns peak memory usage, and getrusage () returns CUP usage. These functions will give you some useful information when debugging PHP code performance. However, please note that one point is invalid on Window in these functions.

Usage:

echo "Initial: ".memory_get_usage()." bytes \n";
echo "Peak: ".memory_get_peak_usage()." bytes \n";
$data = getrusage();
echo "User time: ".
($data['ru_utime.tv_sec'] +
$data['ru_utime.tv_usec'] / 1000000);
echo "System time: ".
($data['ru_stime.tv_sec'] +
$data['ru_stime.tv_usec'] / 1000000);

gzcompress(), gzuncompress()

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

Usage:

$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);

For more readers interested in PHP related contents, please check the topics on this site: "Summary of Common Functions and Skills of php", "Summary of Usage of php String (string)", "Encyclopedia of Operation Skills of PHP Array (Array)", "Introduction to Basic Grammar of PHP", "Introduction to Database Operation of php+mysql" and "Summary of Operation Skills of Common Database of php"

I hope this paper is helpful to everyone's PHP programming.