String segmentation (C ++)

We often encounter the problem of string segmentation. Here we will summarize it for my convenience.

I. UseStrtokFunctionString segmentation

Prototype:Char * strtok (char * STR, const char * delim );

Function:Splits a string into a group of strings.

Parameter description:STrIs the string to be decomposed,DelimIt is a separator string.

Return Value:SlaveSTrSplit strings starting. Returns if no split string exists.Null.

Example:

 1   //  Use strtok to implement split  
  2 # Include < String . H>
 3 # Include <stdio. h>
4  
 5   Int Main ()
 6 {
 7           Char S [] = "  Golden global view, disk * desk  " ;
 8           Const   Char * D = "  ,* " ;
 9           Char * P;
 10 P = strtok (S, d );
 11           While (P)
 12 {
 13 Printf ( "  % S \ n  " , P );
 14 P = strtok (null, d );
15 }
 16  
 17           Return   0 ;
 18 }

 Running effect: 

Ii. UseSTLString segmentation 

The following two functions are involved: Find and substr:
1. Find function
Prototype: size_t find (const string & STR, size_t Pos = 0) const;
Function: locate the first occurrence of a substring.
Parameter description: STR is a substring, and POS is the initial search position.
Returned value: if it is found, the first position is returned. Otherwise, string: NPOs is returned.

2. substr Function
Prototype: String substr (size_t Pos = 0, size_t n = NPOs) const;
Function: obtain a substring.
Parameter description: POS is the starting position (0 by default), and N is the ending position (NPOs by default)
Return Value: substring

The implementation is as follows:

 1   //  String segmentation Function  
  2 STD: vector <STD :: String > Split (STD :: String STR, STD :: String Pattern)
 3 {
 4 STD :: String : Size_type Pos;
 5 STD: vector <STD :: String > Result;
 6 STR + = pattern; //  Extended string for easy operation  
  7       Int Size = Str. Size ();
 8  
 9       For ( Int I = 0 ; I <size; I ++)
 10 {
 11 Pos = Str. Find (pattern, I );
 12           If (Pos <size)
 13 {
 14 STD :: String S = Str. substr (I, pos-I );
 15 Result. push_back (s );
 16 I = POS + pattern. Size ()- 1 ;
 17 }
 18 }
 19       Return Result;
 20 }

CompleteCode:

View code

 1   /*  
  2   File: split1.cpp
  3  Author: Mike
  4   E-mail: Mike_Zhang@live.com
  5    */ 
 6 # Include <iostream>
 7 # Include < String >
 8 # Include <vector>
 9  
 10   //  String segmentation Function 
  11 STD: vector <STD :: String > Split (STD :: String STR, STD :: String Pattern)
 12 {
 13 STD :: String : Size_type Pos;
 14 STD: vector <STD :: String > Result;
 15 STR + = pattern;//  Extended string for easy operation  
  16       Int Size = Str. Size ();
 17  
 18       For ( Int I = 0 ; I <size; I ++)
 19 {
 20 Pos = Str. Find (pattern, I );
 21          If (Pos <size)
 22 {
 23 STD :: String S = Str. substr (I, pos-I );
 24 Result. push_back (s );
 25 I = POS + pattern. Size ()- 1 ;
 26 }
 27 }
 28      Return Result;
 29 }
 30  
 31   Int Main ()
 32 {
 33 STD :: String STR;
 34 STD: cout < "  Please input STR:  " <STD: Endl;
35       //  STD: CIN> STR;  
  36 Getline (STD: Cin, STR );
 37 STD :: String Pattern;
 38 STD: cout < "  Please input pattern:  " <STD: Endl;
 39       // STD: CIN> pattern;  
  40 Getline (STD: Cin, pattern ); //  Used to obtain strings containing Spaces  
  41 STD: vector <STD :: String > Result = Split (STR, pattern );
 42 STD: cout < "  The result:  " <STD: Endl;
 43      For ( Int I = 0 ; I <result. Size (); I ++)
 44 {
 45 STD: cout <result [I] <STD: Endl;
 46 }
 47  
 48 STD: cin. Get ();
 49 STD: cin. Get ();
50       Return   0 ;
 51 }

Running effect:

3. Use boost to separate strings

Use the regular expression of the boost library to split strings
The implementation is as follows:

 1 STD: vector <STD :: String > Split (STD :: String STR, STD :: String S)
 2 {
 3 Boost: RegEx Reg (S. c_str ());
4 STD: vector <STD :: String > VEC;
 5 Boost: sregex_token_iterator it (Str. Begin (), str. End (), Reg ,- 1 );
 6 Boost: sregex_token_iterator end;
 7           While (It! = End)
 8 {
 9 VEC. push_back (* It ++ );
 10 }
 11           Return VEC;
 12 }

Complete code:

View code

 1   //  BenProgramThe regular expression is used to separate strings.
  2   //  Running Environment vc6.0 + boost Library  
  3   /*  
 4   File: split2.cpp
  5   Author: Mike
  6   E-mail: Mike_Zhang@live.com
  7   */ 
 8 # Include <iostream>
 9 # Include <cassert>
 10 # Include <vector>
 11 # Include <String >
 12 # Include "  Boost/RegEx. HPP  " 
 13  
 14 STD: vector <STD :: String > Split (STD :: String STR, STD :: String S)
 15 {
 16 Boost: RegEx Reg (S. c_str ());
17 STD: vector <STD :: String > VEC;
 18 Boost: sregex_token_iterator it (Str. Begin (), str. End (), Reg ,- 1 );
 19 Boost: sregex_token_iterator end;
 20           While (It! = End)
 21 {
 22 VEC. push_back (* It ++ );
 23 }
 24           Return VEC;
 25 }
 26   Int Main ()
 27 {
 28 STD :: String STR, S;
 29 STR = "  SSS/DDD/ggg/HH  " ;
30 S = "  /  " ;
 31 STD: vector <STD :: String > VEC = Split (STR, S );
 32           For ( Int I = 0 , Size = Vec. Size (); I <size; I ++)
 33 {
 34 STD: cout <VEC [I] <STD: Endl;
 35 }
 36 STD: cin. Get ();
 37 STD: cin. Get ();
 38           Return   0 ;
 39 }

Running effect:

Supplement:

Recently, we found that boost has built-in split functions. If boost is used, it is better to use split directly. I will not talk about it here. The Code is as follows:

# Include <iostream> # Include < String > # Include <Vector> # Include <Boost/algorithm/ String /Classification. HPP> # Include <Boost/algorithm/ String /Split. HPP> Using   Namespace  STD;  Int  Main (){  String S = "  SSS/DDD, ggg  "  ; Vector < String > Vstr; Boost: Split (vstr, S, boost: is_any_of (  "  ,/  "  ), Boost: token_compress_on );  For (Vector < String >:: Iterator it = vstr. Begin (); it! = Vstr. End (); ++ It) cout <* It <Endl;  Return   0  ;} 

Okay, that's all. I hope it will help you.