One 、 Replace content outside the matching range , Requirements are as follows ：

As the title , The current format is ：

 The rules 40：****
 The rules 41：****
 The rules 42：****

...
    
 The rules 50：****
 The rules 51：****

...

Need to delete the following 4 asterisk , Replace with ：（ requirement ： After deleting the asterisk , The number serial number cannot be changed ）

 The rules 40：
 The rules 41：
 The rules 42：

...
    
 The rules 50：
 The rules 51：

...

Two 、 The regular expression is ：

%s/ The rules \([4-9][0-9]\)：\*\*\*\*/ The rules \1：/gc

3、 ... and 、 paraphrase

 Command framework ：
    %s/AAA/BBB/gc    This command is a global match AAA, And replace with BBB,
                     Parameters gc Express ： Every time the user enters Y Confirm replacement , Input N Do not replace , The specific meaning will not be repeated 
                    
 Interpretation of orders ：
    [4-9][0-9]       For matching 2 Characters , The first character range is 4-9, The second character range is 0-9
    \([4-9][0-9]\)   Symbol \(\) The enclosed part represents a whole expression , hinder \1 It means that the expression is put here intact 
                     remarks ：
                        \(\) The enclosed parts are expressed in sequence 1  expression 2  expression 3 Increasing , This command has only one expression ,\1
                     Such as ：
                        \(aa\)\(bb\)\(cc\)
                     among :
                        aa Expression for 1, Use \1 To call 
                        bb Expression for 2, Use \2 To call 
                        cc Expression for 3, Use \3 To call 
    \1               Indicates the above \(\) Enclosed expressions 

Four 、 Core content ： Expression symbols

This deletion / Replace action , Mainly used in regular expressions “ expression ” Options ,

 use   \(\)   Enclosed expressions , Use \1\2\3\... Progressive representation .

    \1    It means the first one 1 Expression 
    \2    It means the first one 2 Expression 
    \3    It means the first one 3 Expression 
    ...