C++ 运算符是Multimap的非成员重载函数。此函数用于检查第一个multimap是否小于其他multimap。
template <class Key, class T, class Compare, class Alloc> bool operator< ( const multimap<Key,T,Compare,Alloc>& lhs, const multimap<Key,T,Compare,Alloc>& rhs );
lhs :第一个multimap对象。
rhs :第二个multimap对象。
如果multimap对象的左侧小于multimap对象的右侧,则返回true,否则返回false。
让我们看一个简单的示例,检查第一个multimap是否小于:
#include <iostream> #include <map> using namespace std; int main() { multimap<char, int> m1; multimap<char, int> m2; m2.emplace('a', 10); if (m1 < m2) cout << "Multimap m1 is less than m2." << endl; m1 = m2; if (!(m1 < m2)) cout << "Multimap m1 is not less than m2." << endl; return 0; }
输出:
Multimap m1 is less than m2. Multimap m1 is not less than m2.
在上面的示例中,有两个multimapm1和m2。 m2包含一个元素,而m1为空。当我们比较两个multimap时,它将显示消息"multimapm1小于m2",将m2分配给m1后,两个multimap具有相等的元素,则它将显示消息"multimapm1不小于m2"。
让我们看一个简单的例子:
#include <map> #include <iostream> int main () { using namespace std; multimap <int, int> m1, m2, m3; int i; typedef pair <int, int> Int_Pair; for (i = 1; i <3; i ++) { m1.insert (Int_Pair (i, i)); m2.insert (Int_Pair (i, i * i)); m3.insert (Int_Pair (i, i - 1)); } if (m1 <m2) cout << "The multimap m1 is less than the multimap m2." << endl; else cout << "The multimap m1 is not less than the multimap m2." << endl; if (m1 <m3) cout << "The multimap m1 is less than the multimap m3." << endl; else cout << "The multimap m1 is not less than the multimap m3." << endl; }
输出:
The multimap m1 is less than the multimap m2. The multimap m1 is not less than the multimap m3.
让我们看一个简单的例子:
#include <iostream> #include <multimap> using namespace std; int main() { multimap<char,int> m1, m2; m1.insert(make_pair('a',10)); m1.insert(make_pair('b',20)); m1.insert(make_pair('c',30)); m2 = m1; cout << (m1 < m2) << endl; m2.insert(make_pair('d',40)); cout << (m1 < m2) << endl; return 0; }
输出:
0 1
在上面的示例中,如果m1小于m2,则它将返回1,否则返回0。
#include <map> #include <iostream> using namespace std; int main () { multimap<int,string> m2; typedef multimap<int,string> login; m2.insert({2040, "xyz@123"}) ; //stored id and password string password; int id; login m1; cout<<"---------Login----------"<<endl<<endl; cout<<"Enter the ID and password: \n"; cin>> id; //Get key cin>> password; //Get value m1.insert({id, password}); //Put them in multimap cout<<"ID and password you have entered: \n"; for (auto it = m1.begin(); it != m1.end(); it++) { cout << (*it).first << " " << (*it).second << endl; } cout<<"ID and Password stored in the system :\n"; for (auto it = m2.begin(); it != m2.end(); it++) { cout << (*it).first << " " << (*it).second << endl; } if (m1 < m2) cout << "\nIncorrect ID or Password..." << endl; else cout << "\nWelcome to your Page..." << endl; return 0; }
输出:
1). ---------Login---------- Enter the ID and password: 1020 xyz ID and password you have entered: 1020 xyz ID and Password stored in the system: 2040 xyz@123 Incorrect ID or Password... 2). ---------Login---------- Enter the ID and password: 2040 xyz@123 ID and password you have entered: 2040 xyz@123 ID and Password stored in the system: 2040 xyz@123 Welcome to your Page...
在上面的示例中,有两个multimapm1和m2。 m1包含存储的ID和密码,第二个multimapm2存储用户输入的ID和密码。它检查m1是否小于m2。如果m1的ID和密码不少于m2,则登录成功,否则登录失败。
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