Automatically sort by key after STL map insert

Source: Internet
Author: User
Recently I started using the STL container and found that the elements in the map are automatically sorted by key after the insert operation. # Include <string>
# Include <iostream>
# Include <map>
Using namespace STD; Int main ()
Map <int, string> mapstudent;
Mapstudent. insert (pair <int, string> (3, "Xiaoming "));
Mapstudent. insert (pair <int, string> (1, "Hua "));
Mapstudent. insert (pair <int, string> (2, "Liu "));
Map <int, string >:: iterator it;
For (IT = mapstudent. Begin (); it! = Mapstudent. End (); It ++)
Int I = it-> first;
String STR = it-> second; Cout <I <Endl;
Return 1;

The output above is:




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