PHP learning notes-Example code about regular expressions in PHP textbooks (Abstract)

<? PHP  /*  POSIX extended regular expression Functions  */          /*  ---------------------------------------------------  */          $ Ereg = '^ [$] [[: Alpha:] _] [[: alnum:] *' ;  Ereg ( $ Ereg , '$ _ Name ', $ Register ); //  Match and store arrays // eregi () case-insensitive         Var_dump ( $ Register ); //  Display Array Structure                  /*  ---------------------------------------------------  */          $ Ereg = 'TT' ;  $ Str = 'Hello, TM' ;  $ Rep_str = Eregi_replace ( $ Ereg , 'TT ',$ Str ); //  If the matching is successful, use TM to replace ereg_replace () in case sensitivity.          Echo   $ Rep_str  ;  /*  ---------------------------------------------------  */          $ Ereg = 'Is' ;  $ Str = 'This is a register book .' ;  $ Arr_str =Spliti ( $ Ereg , $ Str ); //  Split the string. Split () matching by regular expression is case sensitive          Var_dump ( $ Arr_str  );  /*  PCRE is compatible with regular expression functions-PCRE is slightly better than POSIX in terms of efficiency or syntax  */          /*  ---------------------------------------------------  */         $ Preg = '/\ D {3, 4 }-? \ D {7, 8 }/' ;  $ Arr = Array ('20140901', '2014-043212345678 ', '20140901 '); //  Contains element array          $ Preg_arr = Preg_grep ( $ Preg , $ Arr  );  Var_dump ( $ Preg_arr  ); /*  ---------------------------------------------------  */          $ Str = 'This is an example! ' ;  $ Preg = '/\ B \ W {2} \ B /' ;  $ Num1 = Preg_match ( $ Preg , $ Str , $ Str1 ); // Match and return the number of successful results. After the successful match is put into the array, it stops.          Echo   $ Num1 . "<Br/>" ;  Var_dump ( $ Str1  );  Echo "<Br/>" ;  //  Returns the number of successful matches. After successful matches are put into the array, the system does not stop until all matching characters are completed.          $ Num2 = Preg_match_all ( $ Preg ,$ Str , $ Str2  );  Echo   $ Num2 . "<Br/>" ;  Var_dump ( $ Str2  );  /*  ---------------------------------------------------  */          $ Str = '! , $, ^, *, +,., [,], \,/, B, <,>' ; $ Str2 = 'B' ;  //  Automatically escape special regular expressions. If a parameter exists, the characters containing the parameter are also escaped.          $ Match_one = Preg_quote ( $ Str , $ Str2  );  Echo   $ Match_one  ;  /*  --------------------------------------------------- */          $ String = '[B] Bold [/B]' ;  //  Reverse references are used for matching and replacement.          $ B _rst = Preg_replace ('/\ [B \] (. *) \ [\/B \]/I', '<B> $1 </B> ', $ String  );  Echo   $ B _rst  ;  /*  --------------------------------------------------- */          Function C_back ( $ Str  ){  //  Reverse reference              $ Str = "<Font color = $ Str [1]> $ Str [2] </font>" ;  Return   $ Str  ;}  $ String = '[Color = Blue] font blue [/color]';  //  The character to be replaced in the preg_replace_callback function. It is only the same as the preg_replace function.          Echo   Preg_replace_callback ('/\ [Color = (. *) \] (. *) \ [\/color \]/U', "c_back ", $ String  );  /*  ---------------------------------------------------  */          //  No in this function book. I will give you my own examples!          $ Preg = "/\ S + /";//  Here you can also change to "/\ s {1 ,}/";          $ Str = "I'm Chinese! I can eat" ;  $ Arr = Preg_split ( $ Preg , $ Str ); // Search and split. -- There is a written mistake here. The friends I have read can't help but have corrected it now.          Var_dump ( $ Arr  ); ?>