How Can I Efficiently Iterate Through Nested Maps in C ?

Iterating Multiple Maps in C

Navigating through multiple levels of nested maps in C can be a daunting task. This guide provides a comprehensive solution for looping through a container of maps, known as a map of maps.

The approach utilizes the powerful ranged-based for loop, introduced in C 11. Let's delve into the code:

std::map<std::string, std::map<std::string, std::string>> mymap;

for (auto const &ent1 : mymap) {
  for (auto const &ent2 : ent1.second) {
    std::cout << ent1.first << " " << ent2.first << " " << ent2.second << std::endl;
  }
}

In the outer loop, ent1 holds a key-value pair where ent1.first represents the first-level key. The inner loop iterates through the value of ent1.second, which is another map, and ent2 provides access to the key and value of the second-level map.

If you prefer using explicit definitions of reference variables, you can introduce temporary variables like outer_key, inner_key, and inner_value to clarify the purpose of each variable.

C 17 introduces structured bindings, offering a concise syntax to access nested elements. The following code snippet demonstrates this feature:

for (auto const &[outer_key, inner_map] : mymap) {
  for (auto const &[inner_key, inner_value] : inner_map) {
    std::cout << outer_key << " " << inner_key << " " << inner_value << std::endl;
  }
}

In this example, the outer key and value, along with the inner key and value, are directly accessible within the loop body.

By utilizing these techniques, you can effortlessly iterate through multiple levels of nested maps in C . Happy coding!

The above is the detailed content of How Can I Efficiently Iterate Through Nested Maps in C ?. For more information, please follow other related articles on the PHP Chinese website!