set::count
Visual Studio .NET 2003
其他版本
Returns the number of elements in a set whose key matches a parameter-specified key.
size_type count( const Key& _Key ) const;
Parameter
_Key
The key of the elements to be matched from the set.
Return Value
1 if the set contains an element whose sort key matches the parameter key. 0 if the set does not contain an element with a matching key.
Remarks
The member function returns the number of elements in the following range:
[lower_bound (_Key ), upper_bound (_Key ) ).
Example
// set_count.cpp// compile with: /EHsc #include <set> #include <iostream> int main( ) { using namespace std; set <int> s1; int i; s1.insert( 1 ); s1.insert( 1 ); // Keys must be unique in set, so duplicates are ignored i = s1.count( 1 ); cout << "The number of elements in s1 with a sort key of 1 is: " << i << "." << endl; i = s1.count( 2 ); cout << "The number of elements in s1 with a sort key of 2 is: " << i << "." << endl; }
Output
The number of elements in s1 with a sort key of 1 is: 1.The number of elements in s1 with a sort key of 2 is: 0.
