PHP string Regular replacement function preg_replace_php Tutorial

Syntax: Mixed preg_replace (mixed pattern, mixed replacement, mixed subject);

Return value: Mixed type data

Function type: Data processing

Description: This function parses the subject string with the rule of pattern, and the string to be replaced is the parameter replacement. The return value is a mixed-type data, which is substituted for the string result.

1. Preg_replace ()

$msg = Preg_replace ("/ /is", "", $msg); -----Delete and the middle part
$msg = Preg_replace ("/<[^>]+>/", "", $msg); -----is to delete <> and intermediate content

I (pcre_caseless)
If this modifier is set, the characters in the pattern will match the uppercase and lowercase letters.
S (pcre_dotall)
If this modifier is set, the dot character (.) in the pattern matches all characters, including the line break. Without this setting, the line break is not included. This is equivalent to Perl's/s modifier. Exclude character classes such as [^a] always match line breaks, regardless of whether this modifier is set.

2. Ereg () and eregi ()

Note: the Preg_match () function is usually a faster alternative than ereg ()

Eregi (" ]+) > (. +)", $data, $b)----see if there is a body tag in the $data. If so, assign the parameter $b[0], and the middle part assigns a value of $b[1].

BOOL Ereg (string pattern, string string [, array regs])

int eregi (string pattern, string string, array [regs])

Eregi () and Ereg () are similar in usage. The difference is that ereg () is case-sensitive, eregi () is not case-insensitive

Comparison of the use of the Preg_replace () and ereg_replace () functions
-------Preg_replace ()--------------------------
1. Replacing the search for a string
$str = "Daoyu shi ge hao hai zi 5555";
$pattern = "/s/"; If you define a variable as $pattern_1, an error occurs
$str = Preg_replace ($pattern, '-', $str);
echo $str. "
";

2. Inverse reference to a string
Method One
$pat = "/(w+)-(w+)-(w+)-(w+)-(w+)-(w+)-(d+)/I";
$str =preg_replace ($pat, "$", $str);
echo $str. "
";

Note: If it is the following form you will find the match is: zi-so you can think that in the case of a number of {6}, he ($) matches the last
$pat = "/((w+)-) {6} (d+)/I";
$str =preg_replace ($pat, "$", $str);
echo $str. "
";

Method Two
$str = "daoyu-shi-ge-hao-hai-zi-5555";
$pat = "/(w+)-(w+)-(w+)-(w+)-(w+)-(w+)-(d+)/I";
$str =preg_replace ($pat, "1", $str);
echo $str. "
";

Note: When the regular is written $pat= "/((w+)-) {6} (d+)/I";

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