Map每個元素都是 key/value pair ,其中key是排序準則的基準。每個key只能出現一次,不允許重複。Map
也可被視爲一種關聯式數組,也就是“索引可爲任意類型”的數組。
以具體的兩個例子解釋什麼是map
實例一
#include "pch.h"
#include <map>
#include <iostream>
#include <string>
using namespace std;
int main()
{
map<int, string> coll;
coll = { {5, "tagged"},
{2, "a"},
{1, "this"},
{4, "of"},
{6, "strings"},
{1, "is"},
{3, "map"}
};
for (auto elem : coll) {
cout << elem.second << ' ';
}
cout << endl;
getchar();
}
輸出結果是
實例二
#include "pch.h"
#include <map>
#include <iostream>
#include <string>
using namespace std;
int main ()
{
int a[5];
map<int, int>M;
a[0] = 1; M[a[0]]++;
a[1] = 2; M[a[1]]++;
a[2] = 2; M[a[2]]++;
a[3] = 4; M[a[3]]++;
a[4] = 1; M[a[4]]++;
map<int, int>::iterator it;
for (it = M.begin(); it != M.end(); it++)
cout << it->first << ' ' << it->second << endl;
getchar();
return 0;
}
輸出結果是