标签：print   src   第一个   输出   upper   vector   ++i   支持   catch   

//fig15_04.cpp
#include <iostream>
#include <iterator> //ostream_iterator istream_iterator

using namespace std;

//输入两个数 输出两个数的和
int main()
{
    istream_iterator<int> inputInt(cin);//与cin关联上

    int num1 = *inputInt;//接受一个整数
    ++inputInt;//移动到下一个输入值
    int num2 = *inputInt;//接受下一个输入

    ostream_iterator<int> outputInt(cout);//与cout关联上
    cout << "the sum is ";
    *outputInt = num1 + num2;//接受一个输出
    cout << endl;


    return 0;
}

迭代器还可以这么用 ,卧槽!

迭代器的类型

标准容器支持的迭代器

顺序容器

Vector

例子-使用迭代器遍历vector-顺序和逆序

//fig15_10.cpp
#include <iostream>
#include <vector>

using namespace std;

template <typename T>
void printVector(const vector<T>& integers)
{
    for (auto constIterator = integers.cbegin();
        constIterator != integers.cend(); ++constIterator)
    {
        cout << *constIterator << " ";
    }
    cout << endl;
}
template <typename T>
void printReverseVector(const vector<T>& integers)
{
    for (auto constReverseIterator = integers.crbegin();
        constReverseIterator != integers.crend(); ++constReverseIterator)
    {
        cout << *constReverseIterator << " ";
    }
    cout << endl;
}

int main()
{

    const size_t SIZE = 6;
    int value[SIZE] = { 1,2,3,4,5,6 };

    vector<int> integers;

    cout << "The initial size of integers is" << integers.size()
        << "\nThe iniial capacity of integers is " << integers.capacity() << endl;

    integers.push_back(2);
    integers.push_back(3);
    integers.push_back(4);

    cout << "The size of integers is" << integers.size()
        << "\nThe capacity of integers is " << integers.capacity() << endl;

    cout << "Display array using  pointer notation:" << endl;

    for (const int* ptr = begin(value); ptr != end(value); ++ptr)
    {
        cout << *ptr << " ";
    }
    cout << endl;

    cout << "Display vector using iterator notation:";
    printVector(integers);

    
    cout << "Display vector in reverse order using  iterator:";
    printReverseVector(integers);

    return 0;
}

例子-操作vector元素

//fig15_11.cpp
#include <iostream>
#include <stdexcept>
#include <array>
#include <vector>
#include <algorithm>
#include <iterator>

using namespace std;

int main()
{
    const size_t SIZE = 6;
    array<int, SIZE> values = { 1,2,3,4,5,6 };

    vector<int> integers(values.cbegin(),values.cend());//使用array来初始化vector

    ostream_iterator<int>output(cout, " ");//通过迭代cout来输出元素,以空格来分隔
    
    //输出
    cout << "Vector integers contains:";
    copy(integers.cbegin(), integers.cend(), output);

    //首尾元素
    //front和back返回的是元素的引用,而begin和end返回的是随机访问迭代器
    if (!integers.empty())//检查vector是否为空,不检查的话 如果integers是空,则运行时报错
    {
        cout << "\nFirst element is " << integers.front() << endl;
        cout << "\nLast element is " << integers.back() << endl;

    }
    
    //随机访问
    integers[0] = 7;
    integers.at(2) = 10;

    //输出
    cout << "Now Vector integers contains:";
    copy(integers.cbegin(), integers.cend(), output);
    cout << endl;//7 2 10 4 5 6

    //在第一个元素后面插入22
    integers.insert(integers.cbegin() + 1, 22);

    //输出
    cout << "Vector integers after change contains:";
    copy(integers.cbegin(), integers.cend(), output);
    cout << endl;//7 22 2 10 4 5 6

    try
    {
        integers.at(200) = 1;//at提供越界检查
    }
    catch (out_of_range&outOfRange)
    {
        cout<<"Exception:"<<outOfRange.what()<<endl;
    }

    //移除首元素
    integers.erase(integers.cbegin());

    //输出
    cout << "Vector integers after erase the first element  contains:";
    copy(integers.cbegin(), integers.cend(), output);
    cout << endl;

    //使用迭代器清空
    integers.erase(integers.cbegin(), integers.cend());
    cout << "\nAfter erasing all elements,vector integers " << (integers.empty() ? "is" : "is not") << " empty" << endl;

    //使用array来插入元素
    integers.insert(integers.cbegin(), values.cbegin(), values.cend());
    cout << "before clear integers contains:";
    copy(integers.cbegin(), integers.cend(), output);
    cout << endl;

    //清空
    integers.clear();
    cout << "\nAfter clear all elements,vector integers " << (integers.empty() ? "is" : "is not") << " empty" << endl;


    return 0;
}

List

//fig15_13.cpp
//List

#include <list>
#include <array>
#include <iostream>
#include <iterator>
#include <stdexcept>

using namespace std;

template <typename T>
void printList(const list<T>& listRef)
{
    if (listRef.empty())
    {
        cout << "list is empty!" << endl;
    }
    else
    {
        ostream_iterator<T> output(cout, " ");
        copy(listRef.cbegin(), listRef.cend(), output);
    }
    cout << endl;
}
int main()
{
    const size_t SIZE = 4;
    array<int, SIZE>ints = { 1,2,3,4 };

    list<int> values;
    list<int> otherValues;

    values.push_front(1);
    values.push_front(2);
    values.push_back(4);
    values.push_back(3);

    cout << "List contains:";
    printList(values);

    //排序
    values.sort();
    cout << "values after sorting contains:";
    printList(values);

    //使用array来插入otherValues
    otherValues.insert(otherValues.cbegin(), ints.cbegin(), ints.cend());
    cout << "After insert ,otherList contains:";
    printList(otherValues);

    //splice做了两步:第一步将othevalues里的值插入到values.cend(),第二步将otherValues里的值清空
    values.splice(values.cend(), otherValues);
    cout << "After splice values contains:";
    printList(values);

    cout << "After splice ,otherValues contains:";
    printList(otherValues);



    otherValues.insert(otherValues.cbegin(), ints.cbegin(), ints.cend());
    cout << "After insert and sort ,otherList contains:";
    otherValues.sort();
    printList(otherValues);

    values.sort();
    //使用merge前,两个容器必须先排序
    //merge也是做了两步,第一步将两个容器归并(类似于归并排序),第二步将otherValues清空
    values.merge(otherValues);
    cout << "After merge values contains:";
    printList(values);

    cout << "After merge otherValues contains:";
    printList(otherValues);
    
    values.pop_front();
    values.pop_back();
    cout << "After pop_front and pop_back values contains:";
    printList(values);

    //去重
    values.unique();
    cout << "After unique, values contains:";
    printList(values);

    //交换
    values.swap(otherValues);
    cout << "After swap values contains:";
    printList(values);

    cout << "After swap otherValues contains:";
    printList(otherValues);

    //赋值
    values.assign(otherValues.cbegin(), otherValues.cend());
    cout << "After assign values contains:";
    printList(values);

    values.push_front(4);
    cout << "After push_front(4) values contains:";
    printList(values);

    //移除所有的4
    values.remove(4);
    cout << "After remove(4) values contains:";
    printList(values);



    return 0;
}

deque

//fig15_14.cpp
//deque 双端队列
#include <iostream>
#include <deque>
#include <algorithm>
#include <iterator>
using namespace std;


int main()
{
    deque<double>values;
    ostream_iterator<double> output(cout, " ");

    //双端
    values.push_front(2.2);
    values.push_front(3.5);
    values.push_back(1.1);

    //随机访问
    cout << "values contains:";
    for (size_t i = 0; i < values.size(); ++i)
    {
        cout << values[i] << " ";
    }

    cout << endl;

    values.pop_front();

    cout << "\nAfter pop_front values contains:";
    copy(values.cbegin(), values.cend(), output);
    cout << endl;

    


    return 0;
}

关联容器

multiset

//fig15_15.cpp
//multi_set
#include <set>
#include <algorithm>
#include <iostream>
#include <iterator>
#include <array>


using namespace std;

int main()
{

    const size_t SIZE = 6;
    array<int, SIZE> a = { 11,21,13,21,54,66 };

    //按照从小到大顺序排序 less<int>
    multiset<int, less<int>> intMultiset;
    ostream_iterator<int> output(cout, " ");

    //count 是说该元素在multiset中含有几个
    cout << "There are currently " << intMultiset.count(15)
        << " values of 15 in the multiset" << endl;//0

    intMultiset.insert(15);
    intMultiset.insert(15);

    cout << "After inserts,there are " << intMultiset.count(15)
        << " values of 15 in the multiset" << endl;//2

    //查找
    auto result = intMultiset.find(15);
    if (result!=intMultiset.end())
    {
        cout << "find 15" << endl;
    }
    result = intMultiset.find(20);
    if (result == intMultiset.end())
    {
        cout << "Not find 20" << endl;
    }

    intMultiset.insert(a.cbegin(), a.cend());
    cout << "\nAfter insert,intMultiset contains:";
    copy(intMultiset.cbegin(), intMultiset.cend(), output);
    cout << endl;


    //确定某个值的边界
    cout << "\nLower bound of 21:" << *(intMultiset.lower_bound(21)) << endl;//下边界
    cout << "\nUpper bound of 21:" << *(intMultiset.upper_bound(21)) << endl;//上边界

    //返回的是pair对象,包含下边界和上边界
    auto p = intMultiset.equal_range(21);
    cout << "lower bound:" <<*p.first << " upper bound:" << *p.second << endl;


    return 0;
}

multimap

//fig15_16.cpp
//multimap
#include <map>
#include <iostream>
#include <iterator>
#include <algorithm>

using namespace std;

int main()
{
    multimap<int, double, less<int>> mymap;

    //count 是说该元素在multiset中含有几个
    cout << "There are currently " << mymap.count(15)
        << " values of 15 in the multiset" << endl;//0

    mymap.insert(make_pair(15, 2.7));
    mymap.insert(make_pair(15, 99.3));

    cout << "After inserts,there are " << mymap.count(15)
        << " values of 15 in the multiset" << endl;//2

    mymap.insert(make_pair(30,111.11));
    mymap.insert(make_pair(10,232));

    //遍历
    for (auto it : mymap)
    {
        cout << it.first << "\t" << it.second << endl;
    }


    return 0;
}

map

//fig15_18.cpp
//map
#include <iostream>
#include <map>

using namespace std;

int main()
{
    map<int, double, less<int>>mymap;

    mymap.insert(make_pair(15, 2.7));
    mymap.insert(make_pair(11, 2.7));
    mymap.insert(make_pair(12, 2.7));
    mymap.insert(make_pair(15, 2.6));//ignored
    mymap.insert(make_pair(15, 2.1));//ignored

    mymap[11] = 11;

    for (auto it : mymap)
    {
        cout << it.first << "\t" << it.second << endl;
    }
    cout << endl;
    return 0;
}

[c++基础]STL

标签：print   src   第一个   输出   upper   vector   ++i   支持   catch   

原文地址：https://www.cnblogs.com/tailiang/p/11659838.html