c++ map values range

To map values within a range in C++, you can use a combination of the std::map container and iterator-based algorithms. Here are the steps involved:

  1. Include the necessary header files: To use the std::map container, you need to include the <map> header file in your code.

  2. Create a std::map object: Declare and instantiate a std::map object that will store your key-value pairs. The keys in the map should be unique and ordered.

  3. Insert values into the map: Use the insert() function or the square bracket [] operator to insert key-value pairs into the map. The keys will determine the ordering of the values.

  4. Find the range: Determine the range of values you want to map. This can be done using the lower_bound() and upper_bound() member functions of the std::map container. The lower_bound() function returns an iterator pointing to the first element that is not less than a given key, while the upper_bound() function returns an iterator pointing to the first element greater than a given key.

  5. Iterate over the range: Use a loop to iterate over the range of values you obtained from the previous step. You can use the begin() and end() member functions of the std::map container to get iterators representing the beginning and end of the map.

  6. Perform operations on the mapped values: Within the loop, you can access and perform operations on the mapped values using the iterator. You can use the -> operator to access the value associated with the iterator.

Here is an example that demonstrates these steps:

#include <iostream>
#include <map>

int main() {
    std::map<int, std::string> myMap;

    myMap.insert({1, "One"});
    myMap.insert({2, "Two"});
    myMap.insert({3, "Three"});
    myMap.insert({4, "Four"});
    myMap.insert({5, "Five"});

    auto lower = myMap.lower_bound(2);
    auto upper = myMap.upper_bound(4);

    for (auto it = lower; it != upper; ++it) {
        std::cout << it->second << std::endl;

    return 0;

In this example, we create a std::map called myMap and insert five key-value pairs into it. We then use lower_bound(2) to get an iterator pointing to the element with the key 2, and upper_bound(4) to get an iterator pointing to the element with the key 4. Finally, we iterate over the range from lower to upper and print the corresponding values.

The output of this code will be:


This demonstrates how you can map values within a specific range using a std::map in C++.