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Check if a key is present in a C++ map or unordered_map
In C++ the Maps and unordered maps are hash tables. They use some keys and their respective key values. Here we will see how to check whether a given key is present in the hash table or not. The code will be like below −
Example
#include<iostream> #include<map> using namespace std; string isPresent(map<string, int> m, string key) { if (m.find(key) == m.end()) return "Not Present"; return "Present"; } int main() { map<string, int> my_map; my_map["first"] = 4; my_map["second"] = 6; my_map["third"] = 6; string check1 = "fifth", check2 = "third"; cout << check1 << ": " << isPresent(my_map, check1) << endl; cout << check2 << ": " << isPresent(my_map, check2); }
Output
fifth: Not Present third: Present
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