Map and multimap are both self-contained find () and can be searched without generic algorithm. In fact, when both container and algorithm provide methods, we should first test the container self-belt method. Because algorithm still needs iterator to test the generic model, but the container self-belt method is tailor-made, therefore, the compaction speed is faster.
There are three methods to list all values of a key in multimap. This example shows how to use these three methods.
1 /**/ /*
2 (C) oomusou 2006 Http://oomusou.cnblogs.com
3
4 Filename: multimapfindbykey. cpp
5 Compiler: Visual C + + 8.0/iso c ++
6 Description: Demo how to find by key in multimap
7 Release: 12/16/2006 1.0
8 */
9 # Include < Iostream >
10 # Include < Map >
11 # Include < String >
12
13 Using Namespace STD;
14
15 Int Main () {
16 Typedef multimap < String , String > Authorbooks;
17 Authorbooks;
18
19 Authorbooks. insert (make_pair ( " Stanley B. Lippman " , " C ++ Primer " ));
20 Authorbooks. insert (make_pair ( " Stanley B. Lippman " , " Essential tail C ++ " ));
21 Authorbooks. insert (make_pair ( " Scott Meyers " , " Valid C ++ " ));
22 Authorbooks. insert (make_pair ( " Andrei Alexandrescu " , " Modern C ++ Design " ));
23
24 String Searchitem = " Stanley B. Lippman " ;
25
26 // Find all values by key using count & find
27 Authorbooks: size_type entries = Authorbooks. Count (searchitem );
28 Authorbooks: iterator ITER = Authorbooks. Find (searchitem );
29 For (Authorbooks: size_type CNT = 0 ; CNT ! = Entries; ++ CNT)
30 Cout < ITER ++-> Second < Endl;
31
32 Cout < Endl;
33 Cout < Endl;
34
35 // Find all values by key using lower_bound (), upper_bound ();
36 Authorbooks: iterator beg = Authorbooks. lower_bound (searchitem );
37 Authorbooks: iterator end = Authorbooks. upper_bound (searchitem );
38
39 While (Beg ! = End)
40 Cout < Beg ++-> Second < Endl;
41
42 Cout < Endl;
43 Cout < Endl;
44
45 // Find all values by key using sort _range ()
46 Typedef authorbooks: iterator iterab;
47 Pair < Iterab, iterab > Pos = Authorbooks. searchitem );
48 While (Pos. First ! = POs. Second)
49 Cout < POs. First ++-> Second < Endl;
50
51 Return 0 ;
52 }
In addition to using the count () + find () program, the lower_bound ()/upper_bound () and pai_range () programs have almost the same length, so there is no special suggestion.
