Implementing Multidimensional Map in C++ Last Updated : 12 Jul, 2025 Summarize Comments Improve Suggest changes Share Like Article Like Report Multidimensional maps are used when we want to map a value to a combination of keys. The key can be of any data type, including those that are user-defined. Multidimensional maps are nested maps; that is, they map a key to another map, which itself stores combinations of key values with corresponding mapped values. Syntax: // Creating a two-dimensional map: map< key_1_type, map< key_2_type, value_type> > object; // Creating an N-dimensional map: map< key_1_type, map< key_2_type, ... map< key_N_type, value_type> > > object; Example 1: CPP14 // C++14 code to implement two-dimensional map #include <bits/stdc++.h> using namespace std; int main() { // Two-dimensional key map<int, map<int, int> > m; // For accessing outer map map<int, map<int, int> >::iterator itr; // For accessing inner map map<int, int>::iterator ptr; for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { m[i][j] = i + j; } } for (int i = 0; i < 2; i++) { for (int j = 0; j < 2; j++) { // Accessing through array subscript cout << "First key is " << i << " And second key is " << j << " And value is " << m[i][j] << endl; } } cout << "\nNow accessing map though iterator \n\n"; for (itr = m.begin(); itr != m.end(); itr++) { for (ptr = itr->second.begin(); ptr != itr->second.end(); ptr++) { cout << "First key is " << itr->first << " And second key is " << ptr->first << " And value is " << ptr->second << endl; } } } Output: First key is 0 And second key is 0 And value is 0 First key is 0 And second key is 1 And value is 1 First key is 1 And second key is 0 And value is 1 First key is 1 And second key is 1 And value is 2 Now accessing map though iterator First key is 0 And second key is 0 And value is 0 First key is 0 And second key is 1 And value is 1 First key is 1 And second key is 0 And value is 1 First key is 1 And second key is 1 And value is 2 Example 2: CPP14 // C++14 code to implement two-dimensional map // and inserting value through insert() #include <bits/stdc++.h> using namespace std; int main() { // First key type is a string map<string, map<int, int> > m; map<string, map<int, int> >::iterator itr; map<int, int>::iterator ptr; m.insert(make_pair("Noob", map<int, int>())); m["Noob"].insert(make_pair(0, 5)); m.insert(make_pair("Geek", map<int, int>())); m["Geek"].insert(make_pair(1, 10)); m.insert(make_pair("Geek", map<int, int>())); m["Geek"].insert(make_pair(2, 20)); for (itr = m.begin(); itr != m.end(); itr++) { for (ptr = itr->second.begin(); ptr != itr->second.end(); ptr++) { cout << "First key is " << itr->first << " And second key is " << ptr->first << " And value is " << ptr->second << endl; } } } Output: First key is Geek And second key is 1 And value is 10 First key is Geek And second key is 2 And value is 20 First key is Noob And second key is 0 And value is 5 Comment More infoAdvertise with us Next Article Descending Order in Map and Multimap of C++ STL G gyanendra371 Follow Improve Article Tags : C++ cpp-map-functions Practice Tags : CPP Similar Reads Multidimensional Vectors in C++ A multidimensional vector is a vector of vectors that allows us to create 2D, 3D, or higher-dimensional vectors in a similar way as multidimensional arrays but unlike arrays, multidimensional vectors can grow and shrink dynamically.Let's take a quick look at a simple example of a multidimensional ar 7 min read How to print dimensions of multidimensional array in C++ Create a function that prints multidimensional array size by dimensions i.e.:Examples: Input : int a[2][3][4]; printDimensions(a); Output : 2x3x4 Input : int b[5][6]; printDimensions(a); Output : 5x6 To solve this problem we should use template function to figure out the size of current array. 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