Detailed explanation of 7 practical PHP function usage examples-PHP Tutorial-php.cn

Detailed explanation of 7 practical PHP function usage examples

伊谢尔伦

Release： 2023-03-11 22:42:01

Original

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This article recommends 7 php built-in functions that are not often used, but are actually very practical and powerful. If you use them well, you can save a lot of time.

PHP has many built-in functions, most of which are widely used by programmers. But there are also some functions hidden in the corners. This article will introduce to you 7 functions that are little known but very useful. Programmers who have never used it may wish to come and take a look.

　1.highlight_string()

When you need to display PHP code in a website, the highlight_string() function changes Very useful. This function outputs or returns a syntax-highlighted version of the given PHP code, using the colors defined in the PHP syntax highlighter.

Example:

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

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2.str_word_count()

This function must pass a parameter and return it according to the parameter type The number of words. As shown below:

<?php
$str = "How many words do I have?";
echo str_word_count($str); //Outputs 6
?>

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　3.levenshtein()

This function mainly returns two

strings Levenshtein distance between. Levenshtein distance, also known as edit distance, refers to the minimum number of edit operations required between two strings to convert one into the other. Permitted editing operations include replacing one character with another, inserting a character, and deleting a character. This function is useful for finding typos submitted by users.

Example:

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

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4.get_defined_vars()

This function returns a list containing all

defined variables ##Multidimensional array, these variables include environment variables, server variables and user-defined variables. Example:

print_r(get_defined_vars());

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5.escapeshellcmd()

This function is used to escape special symbols in strings and prevent users from playing tricks. to crack the server system. You can use this function with the exec() or system() functions, which can reduce the malicious destructive behavior of online users.

Example:

<?php
$command = &#39;./configure &#39;.$_POST[&#39;configure_options&#39;];
$escaped_command = escapeshellcmd($command);
system($escaped_command);
?>

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6.checkdate()

This function can be used to check whether the date is valid, for example, the year is 0 to 32767, The months range from January to December, and the days change with the months and leap years.

Example:

<?php
var_dump(checkdate(12, 31, 2000));
var_dump(checkdate(2, 29, 2001));
//Output
//bool(true)
//bool(false)
?>

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7.php_strip_whitespace()

This function can return the deleted

PHP comment

and whitespace characters Source code files, which is useful for comparing the actual amount of code versus the number of comments. Example:

<?php
// PHP comment here
/*
 * Another PHP comment
 */
echo        php_strip_whitespace(FILE);
// Newlines are considered whitespace, and are removed too:
do_nothing();
?>

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Output result:

<?php
 echo php_strip_whitespace(FILE); do_nothing(); 
?>

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