STL::map默认会按照.first的字母顺序排列

 看个代码:

// map默认会按照.first的字母顺序排列

#include 
#include 
#include 

using namespace std;

int main()
{
    map map1;
    map::iterator mapit;
    map::iterator saveit;
	
    map1["fab"] = "2";
    map1["dja"] = "3";
    map1["dfe"] = "4";
    map1["tw"] = "5";

	cout << "Map size: " << map1.size() << endl;
	
    mapit = map1.begin();
    while (mapit != map1.end()) 
	{
        cout << "Element key: " << mapit->first << ", value: " << mapit->second << endl;
        mapit++;
    }

    return 0;
}


运行结果:

Map size: 4
Element key: dfe, value: 4
Element key: dja, value: 3
Element key: fab, value: 2
Element key: tw, value: 5
Press any key to continue


看到了吗,map中的first成员被按字母顺序给输出来了!

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