unordered_multimap::hash_function()是C++ STL中的内置函数，用于获取哈希函数。该哈希函数是一元函数，仅接受单个参数，并基于该参数返回一个唯一的大小为size_t的值。
用法：
unordered_multimap_name.hash_function()
参数：该函数不接受任何参数。
返回值：该函数返回哈希函数。
以下示例程序旨在说明unordered_multimap::hash_function()函数：
程序1：
// C++ program to illustrate the
// unordered_multimap::hash_function()
#include <iostream>
#include <unordered_map>
using namespace std;
int main()
{
// declaration
unordered_multimap<string, string> sample;
// inserts key and elements
sample.insert({ "gopal", "dave" });
sample.insert({ "gopal", "dave" });
sample.insert({ "gopal", "dave" });
sample.insert({ "geeks", "geeks" });
// use of hash_function
unordered_multimap<string, string>::hasher fn
= sample.hash_function();
cout << fn("geeks") << endl;
// print the key and elements
cout << "Key and Elements: ";
for (auto it = sample.begin(); it != sample.end(); it++) {
cout << "{" << it->first << ":"
<< it->second << "}, ";
}
return 0;
}
输出：
15276750567035005396
Key and Elements: {geeks:geeks}, {gopal:dave}, {gopal:dave}, {gopal:dave},
程序2：
// C++ program to illustrate the
// unordered_multimap::hash_function()
#include <iostream>
#include <unordered_map>
using namespace std;
int main()
{
// declaration
unordered_multimap<string, string> sample;
// insertion of key and elements
sample.insert({ "gopal", "dave" });
sample.insert({ "geeks", "geeks" });
// use of hash_function
unordered_multimap<string, string>::hasher fn
= sample.hash_function();
cout << fn("geeksforgeeks") << endl;
// print the key and elements
cout << "Key and Elements: ";
for (auto it = sample.begin(); it != sample.end(); it++) {
cout << "{" << it->first << ":"
<< it->second << "}, ";
}
return 0;
}
输出：
5146686323530302118
Key and Elements: {geeks:geeks}, {gopal:dave},
相关用法
注：本文由纯净天空筛选整理自gopaldave大神的英文原创作品 unordered_multimap hash_function() in C++ STL。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。