此函数用于检查第一组是否小于其他组。
template <class T, class Compare, class Alloc> bool operator< ( const set<T,Compare,Alloc>& lhs, const set<T,Compare,Alloc>& rhs );
lhs :第一个设置的对象。
rhs :第二组对象。
如果设置对象的左侧小于设置对象的右侧,则返回true,否则返回false。
让我们看一个简单的示例,检查第一个集合是否小于:
#include <iostream> #include <set> using namespace std; int main() { set<char> m1; set<char> m2; m2.emplace('a'); if (m1 < m2) cout << "Set m1 is less than m2." << endl; m1 = m2; if (!(m1 < m2)) cout << "Set m1 is not less than m2." << endl; return 0; }
输出:
Set m1 is less than m2. Set m1 is not less than m2.
在上面的示例中,有两组m1和m2。 m2包含一个元素,而m1为空。当我们比较两个集合时,它将显示消息"集合m1小于m2",并且在将m2分配给m1之后,两个集合具有相等的元素,然后它将显示消息"集合m1不小于m2"。
让我们看一个简单的例子:
#include <set> #include <iostream> int main () { using namespace std; set <int> m1, m2, m3; int i; for (i = 1; i <3; i ++) { m1.insert (i); m2.insert (i * i); m3.insert (i - 1); } if (m1 <m2) cout << "The set m1 is less than the set m2." << endl; else cout << "The set m1 is not less than the set m2." << endl; if (m1 <m3) cout << "The set m1 is less than the set m3." << endl; else cout << "The set m1 is not less than the set m3." << endl; }
输出:
The set m1 is less than the set m2. The set m1 is not less than the set m3.
让我们看一个简单的例子:
#include <iostream> #include <set> using namespace std; int main() { set<int> s1, s2; s1.insert(10); s1.insert(20); s1.insert(30); s2 = s1; cout << (s1 < s2) << endl; s2.insert(40); cout << (s1 < s2) << endl; }
输出:
0 1
在上面的示例中,如果集合s1小于s2,则它将返回1,否则返回0。
#include <set> #include <iostream> using namespace std; int main () { set<string> m2; typedef set<string> login; m2.insert("xyz@123") ; //stored password string password; login m1; cout<<"---------Login----------"<<endl<<endl; cout<<"Enter the password: \n"; cin>> password; //Get value m1.insert(password); //Put them in set cout<<"Password you have entered: \n"; for (auto it = m1.begin(); it != m1.end(); it++) { cout << (*it)<< endl; } cout<<"Password stored in the system :\n"; for (auto it = m2.begin(); it != m2.end(); it++) { cout << (*it)<< endl; } if (m1 < m2) cout << "\nIncorrect Password..." << endl; else cout << "\nWelcome to your Page..." << endl; return 0; }
输出:
1). ---------Login---------- Enter the password: xyz@123 Password you have entered: xyz@123 Password stored in the system : xyz@123 Welcome to your Page... 2). ---------Login---------- Enter the password: abc@123 Password you have entered: abc@123 Password stored in the system: xyz@123 Incorrect Password...
在上面的示例中,有两组m1和m2。 m1包含密码,第二组m2存储用户输入的密码。它检查m1是否小于m2。如果密码m1不小于m2,则登录成功,否则登录失败。
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