1、rbegin、rend——容器逆序输出的头和尾
#include <iostream>
#include <set>
#include <iomanip>
#include <string>
using namespace std;
template <class T>
class Member
{
public:
Member(T l, T f) : last(l), first(f) {}
void print() const // const !!!
{
cout.setf(ios::left);
cout << setw(15) << first.c_str()
<< last << endl;
}
private:
T first, last;
// const !!!
friend bool operator < (const Member& m1, const Member& m2)
{
return (m1.last < m2.last) ? true : false;
}
friend bool operator == (const Member& m1, const Member& m2)
{
return (m1.last == m2.last) ? true : false;
}
};
//===============================================
int main ()
{
typedef Member<string> M;
typedef set<M, less<M> > S;
M m("Frost","Robert");
S s;
s.insert(m);
s.insert(M("Smith","John"));
s.insert(M("Amstrong","Bill"));
s.insert(M("Bain","Linda"));
S::iterator It = s.begin();
while ( It != s.end() )
(It++)->print();
cout << endl;
S::reverse_iterator rI = s.rbegin();
while ( rI != s.rend() )
(rI++)->print();
return 0;
}
运行结果:
// Bill Amstrong
// Linda Bain
// Robert Frost
// John Smith
//
// John Smith
// Robert Frost
// Linda Bain
// Bill Amstrong
2、size——返回容器内元素的个数
#include <iostream>
#include <set>
using namespace std;
void print (set<int, less<int> >& s)
{
set<int, less<int> >::iterator It;
for ( It = s.begin(); It != s.end(); It++ )
cout << *It << " ";
cout << endl;
}
//--------------------------------------------
int main ()
{
int ary[] = {1,2,3,2,3,4,8,2,5,6};
set<int, less<int> > s;
s.insert(ary,ary+10);
cout << "Size of set s = " << s.size() << endl;
print(s);
s.clear();
cout << "Size of set s = " << s.size() << endl;
return 0;
}
运行结果:
// Size of set s = 7
// 1 2 3 4 5 6 8
// Size of set s = 0
3、swap——将自身容器的内容与指定容器的内容交换
#include <iostream>
#include <set>
#include <algorithm>
using namespace std;
void print (set<int, less<int> >& s)
{
copy(s.begin(),s.end(),
ostream_iterator<int>(cout," "));
cout << endl;
}
//--------------------------------------------
int main ()
{
int ary1[] = {1,2,3,2,3,4,8,2,5,6};
int ary2[] = {5,0,9,2,3,4,8,2,5,6};
set<int, less<int> > s1, s2;
s1.insert(ary1,ary1+10);
cout << "s1 : ";
print(s1);
cout << "s2 : ";
s2.insert(ary2,ary2+10);
print(s2);
if ( s1 != s2 )
s1.swap(s2);
cout << "s1 : ";
print(s1);
cout << "s2 : ";
print(s2);
return 0;
}
运行结果:
// s1 : 1 2 3 4 5 6 8
// s2 : 0 2 3 4 5 6 8 9
// s1 : 0 2 3 4 5 6 8 9
// s2 : 1 2 3 4 5 6 8
4、返回一个用于比较元素间的值的函数对象
#include <iostream>
#include <set>
using namespace std ;
template
void truefalse(T t)
{
cout << (t?"True":"False") << endl;
}
int main ()
{
set<int> s;
cout << "s.value_comp()(1,2) returned ";
truefalse(s.value_comp()(1,2)); // True
cout << "s.value_comp()(2,1) returned ";
truefalse(s.value_comp()(2,1)); // False
cout << "s.value_comp()(1,1) returned ";
truefalse(s.value_comp()(1,1)); // False
return 0;
}
运行结果:
// s.value_comp()(1,2) returned True
// s.value_comp()(2,1) returned False
// s.value_comp()(1,1) returned False
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