replacewith PHP string regular replacement function preg_replace usage instructions

1. preg_replace()
$msg = preg_replace("//is", "", $msg); -----Delete and the middle part
$msg = preg_replace("/<[^>]+>/", "", $msg); ----- is to delete <> and the middle content
i ( PCRE_CASELESS)
If this modifier is set, the characters in the pattern will match both uppercase and lowercase letters.
s (PCRE_DOTALL)
If this modifier is set, the dot metacharacter (.) in the pattern matches all characters, including newlines. Without this setting, newline characters are not included. This is equivalent to Perl's /s modifier. Excluded character classes such as [^a] always match newlines, regardless of whether this modifier is set.
2. ereg() vs. eregi()
Note: The preg_match() function is usually a faster alternative than ereg()
eregi("]+)>(.+)< ;/body>",$data,$b)----Check whether there is a body tag in $data. If so, assign the parameter $b[0] and the middle part $b[1].
bool ereg ( string pattern, string string [, array regs] )
int eregi ( string pattern, string string, array [regs] )
eregi() is similar to ereg() and has the same usage. The difference is that ereg() is case-sensitive, while eregi() is case-independent.

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