hash map - C++

C++11 standard

2026-01-12

Written by: xiaobin

• IDE: VS2022

example

#include <iostream>
#include <unordered_map>
using namespace std;

int main() {

    // Creating an unordered_map with integer
    // keys and string values
    unordered_map<int, string> um =
    { {1, "Geeks"}, {2, "For"}, {3, "C++"} };

    for (auto i : um)
        cout << i.first << ": " << i.second
        << endl;
    return 0;
}

vs2015

Error (active)		no operator "<<" matches these operands	ConsoleApplication2	
c:\Users\hp25nov\Documents\Visual Studio 2015\Projects\ConsoleApplication1\ConsoleApplication2\ConsoleApplication2.cpp	17

Error	C2059	syntax error: '['	ConsoleApplication2	
c:\users\hp25nov\documents\visual studio 2015\projects\consoleapplication1\consoleapplication2\consoleapplication2.cpp	31

Ref

• std::unordered_map
• Unordered Map in C++ STL