C++11 Nested Map with List-Initialization
c++, c++11, dictionary, initialization, initializer-list
Solution
You're just missing a pair of braces around the inner map contents:
map<int, map<int, string>> level2map = {
{0, {
{0, "zero"},
{1, "one"},
{2, "two"}
}},
{1, {
{0, "ZERO"},
{1, "ONE"},
{2, "TWO"}
}}
};
Perhaps it would be more noticeable if you wrote it out in one line. A list of four things:
{0, {0, "zero"}, {1, "one"}, {2, "two"}}
vs. a list of 2 things, where the 2nd thing is a list of 3 things:
{0, {{0, "zero"}, {1, "one"}, {2, "two"}}}
Problem
I have a nested map, i.e., `map<int, map<int, string>>` that I'd like to initialize with an initializer list. I can use an initializer list to initialize a single-level map, but can't seem to figure out the proper syntax for a nested map. Is it even possible? MWE: ``` // This example shows how to initialize some maps // Compile with this command: // clang++ -std=c++11 -stdlib=libc++ map_initialization.cpp -o map_initialization #include <iostream> #include <map> #include <string> using namespace std; int main(){ cout << "\nLearning map initialization.\n" << endl; map<int, string> level1map = { {1, "a"}, {2, "b"}, {3, "c"} }; for (auto& key_value : level1map) { cout << "key: " << key_value.first << ", value=" << key_value.second << endl; } // This section doesn't compile // map<int, map<int, string>> level2map = { // {0, // {0, "zero"}, // {1, "one"}, // {2, "two"} // }, // {1, // {0, "ZERO"}, // {1, "ONE"}, // {2, "TWO"} // } // }; return 0; } ```