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How to create an unordered_set of user defined class or struct in C++?
In this tutorial, we will be discussing a program to understand how to create an unordered set of user defined class or struct in C++.
For this we will create a structure type and then compare two structure types with the function defined by the user to store the hash function.
Example
#include <bits/stdc++.h>
using namespace std;
//defined structure
struct Test {
int id;
bool operator==(const Test& t) const{
return (this->id == t.id);
}
};
//defined class for hash function
class MyHashFunction {
public:
size_t operator()(const Test& t) const{
return t.id;
}
};
int main(){
Test t1 = { 110 }, t2 = { 102 }, t3 = { 101 }, t4 = { 115 };
//defining unordered set
unordered_set<Test, MyHashFunction> us;
us.insert(t1);
us.insert(t2);
us.insert(t3);
us.insert(t4);
for (auto e : us) {
cout << e.id << " ";
}
return 0;
}Output
115 101 110 102
Updated on: 25-Feb-2020
415 Views
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