C++ Map Insert Question

Introduction

Write a program that defines a map of strings and integers.

Insert an element into a map using the map's .insert() member function.

Then use the map's operator [] to insert another key-value element into a map.

Print the map content afterward.

You can use the following code structure: 

#include <iostream> 

int main() 
{ 

} 



#include <iostream> 
#include <map> 
#include <string> 

int main() 
{ 
     std::map<std::string, int> mymap = { {"red", 1}, {"green", 20},  
     {"blue", 15} }; 
    mymap.insert({ "magenta", 4 }); 
    mymap["yellow"] = 5; 

    for (const auto& el : mymap) 
    { 
        std::cout << el.first << ' ' << el.second << '\n'; 
    } 
}

When using the map's [] operator, there are two scenarios.

The key inside the [] operator exists in the map.

This means we can use it to change the value of an element.

The key does not exist.

In this case, when using the map's operator [], the key-value gets inserted into the map.

This was the case with our: mymap["yellow"] = 5; statement.

Remember, maps are graphs, and the map's elements are sorted based on a key.

And since our keys are strings, the order does not necessarily need to be the one we provided in the initializer list.

If, for example, we have a map of ints and strings, and we provide sorted int keys in the initializers list, the order would be the same when printing out the elements: 

#include <iostream> 
#include <map> 
#include <string> 

int main() /* www .  ja v a2s .  co m*/
{ 
     std::map<int, std::string> mymap = { {1, "First"}, {2, "Second"},   
     {3, "Third"}, {4, "Fourth"} }; 

    for (const auto& el : mymap) 
    { 
        std::cout << el.first << ' ' << el.second << '\n'; 
    } 
}



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