C++ std operator == 是C++中设置的非成员重载函数。此函数用于检查两组是否相等。
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等于设置对象的右侧,则返回true,否则返回false。
让我们看一个简单的示例来检查两个集合是否相等:
#include <iostream> #include <set> using namespace std; int main() { set<char> m1; set<char> m2; if (m1 == m2) cout << "Both sets are equal." << endl; m1.emplace('a'); //after adding element in set m1 if (!(m1 == m2)) cout << "Both sets are not equal." << endl; return 0; }
输出:
Both sets are equal. Both sets are not equal.
在上面的示例中,集合m1和m2为空。因此,operator ==将返回true,并且在集合m1中添加一个元素后,m1的大小将变得不同于m2的大小。因此,它将返回false。
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 = 0; i <3; i ++) { m1.insert (i); m2.insert (i * i); m3.insert (i); } if (m1 == m2) cout << "The sets m1 and m2 are equal." << endl; else cout << "The sets m1 and m2 are not equal." << endl; if (m1 == m3) cout << "The sets m1 and m3 are equal." << endl; else cout << "The sets m1 and m3 are not equal." << endl; return 0; }
输出:
The sets m1 and m2 are not equal. The sets m1 and m3 are equal.
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:
1 0
在上面的示例中,如果集合s1和s2相等,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 = {"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 << "\nWelcome to your Page..." << endl; else cout << "\nIncorrect Password..." << endl; return 0; }
输出:
1). ---------Login---------- Enter the password: xyz Password you have entered: xyz Password stored in the system : xyz@123 Incorrect Password... 2). ---------Login---------- Enter the password: xyz@123 Password you have entered: xyz@123 Password stored in the system : xyz@123 Welcome to your Page...
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。它检查这两个集合是否具有相同的元素。如果密码匹配,则登录成功,否则登录失败。
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