# <typeindex>

**[<typeindex>](https://en.cppreference.com/w/cpp/header/typeindex)** provides `std::type_index`, a hashable wrapper around `std::type_info` from `<typeinfo>`. Use it to store types in containers like `std::map` or `std::unordered_map`.

You rarely need this; it's mainly useful for dynamic type dispatch or plugin systems.

## Example

This example uses type_index as a map key to associate types with their string names.

```cpp
// compile: g++ -std=c++11 -o typeindexexample typeindexexample.cpp
// run: ./typeindexexample
// description: use types as map keys

#include <typeindex>
#include <map>
#include <iostream>

int main() {
    std::map<std::type_index, std::string> type_names;
    
    type_names[std::type_index(typeid(int))] = "integer";
    type_names[std::type_index(typeid(double))] = "floating point";
    
    std::cout << "int is: " << type_names[std::type_index(typeid(int))] << "\n";
    
    return 0;
}
```