unordered_set hash_function() in C++ STL
The unordered_set::hash_function() is a built-in function in C++ STL which is used to get hash function. This hash function is a unary function which takes asingle argument only and returns a unique value of type size_t based on it.
Syntax:
unordered_set_name.hash_function()
Parameter: The function accepts no parameter.
Return Value: The function returns the hash function.
Below programs illustrate the unordered_set::hash_function() function:
Program 1:
// CPP program to illustrate the // unordered_set::hash() function #include <iostream> #include <string> #include <unordered_set> using namespace std; int main() { unordered_set<string> sampleSet = { "geeks1", "for", "geeks2" }; // use of hash_function unordered_set<string>::hasher fn = sampleSet.hash_function(); cout << fn("geeks") << endl; for (auto it = sampleSet.begin(); it != sampleSet.end(); it++) { cout << *it << " "; } cout << endl; return 0; } |
Output:
15276750567035005396 geeks2 geeks1 for
Program 2:
// CPP program to illustrate the // unordered_set::hash() function #include <iostream> #include <string> #include <unordered_set> using namespace std; int main() { unordered_set<string> sampleSet; // use of hash_function unordered_set<string>::hasher fn = sampleSet.hash_function(); cout << fn("geeksforgeeks") << endl; return 0; } |
Output:
5146686323530302118
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