Vector详解

一、基本用法(pop_back( ),push_back(value))

基本使用方法：

pop_back() 删除vector的最后一个元素

push_back(value) 将value放到vector的最后

#include<iostream>#include<vector>using namespace std;int main(){    vector<int> myvector;    for(int i=1;i<=10;i++)        myvector.push_back(i);    myvector.pop_back();    return 0;}

二、front(),back(),clear(),empty(),size()

基本用法：

front() 返回对第一个元素的引用

back() 返回对最后一个元素的引用

clear() 清空 vector 

empty() 如果为空，返回 true，否则返回 false

size() 返回 vector 中元素的个数

#include<iostream>#include<vector>using namespace std;int main(){    vector<int> myvector;    for(int i=1;i<=10;i++)        myvector.push_back(i);    cout<<"size="<<myvector.size()<<endl;    cout<<"front="<<myvector.front()<<endl;    cout<<"back="<<myvector.back()<<endl;    if(!myvector.empty()){        myvector.clear();        cout<<"clear!"<<endl;    }    cout<<"size="<<myvector.size()<<endl;    return 0;}

代码运行如下：

三、begin(),end()

begin() 返回指向第一个元素的迭代器(iterator)

end() 返回指向最后一个元素的迭代器

#include<iostream>#include<vector>using namespace std;int main(){    vector<int> myvector;    vector<int>::iterator it;    for(int i=1;i<=10;i++)        myvector.push_back(i);    cout<<"myvector:";    for(it=myvector.begin();it!=myvector.end();it++)        cout<<' '<<*it;    cout<<endl;    return 0;}

代码运行如下：

四、rbegin(),rend()

rebigin() 返回指向末尾的逆向迭代器 

rend() 返回指向开头之前位置的逆向迭代器 

#include<iostream>#include<vector>using namespace std;int main(){    vector<int> myvector (5);    vector<int>::reverse_iterator it;    int i=0;    for(it=myvector.rbegin();it!=myvector.rend();it++)        *it=++i;    cout<<"myvector";    for(int i=0;i<myvector.size();i++)        cout<<' '<<myvector[i];    cout<<endl;    return 0;}

代码运行如下：

五、erase()

erase(loc) 删除 loc 所指元素，并返回下一元素迭代器 

erase(start,end) 删除(start,end)元素，并返回最后被删除 元素的下一个迭代器

#include<iostream>#include<vector>using namespace std;int main(){    vector<int> myvector;    for(int i=1;i<=10;i++)        myvector.push_back(i);    cout<<"first";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    myvector.erase(myvector.begin()+1);    cout<<"second";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    myvector.erase(myvector.begin()+1,myvector.end()-3);    cout<<"3rd";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    return 0;}

代码运行如下：

六、insert()

insert(loc,value) 在 loc 位置插入一个 value 并返回其迭代器

insert(loc,num,value) 在 loc 位置插入 num 个 value 

insert(loc,start,end) 在 loc 位置插入[start,end)间的元素插入后元素均后移v

#include<iostream>#include<vector>using namespace std;int main(){    vector<int> myvector(3,100);    vector<int>::iterator it;    cout<<"first";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    it=myvector.begin();    myvector.insert(it,200);    cout<<"second";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    it=myvector.begin();    myvector.insert(it,2,300);    cout<<"3rd";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    vector<int> anthervector(2,400);    myvector.insert(it+2,anthervector.begin(),anthervector.end());    cout<<"4th";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    int marray[]={500,501,502};    myvector.insert(myvector.begin(),marray,marray+3);    cout<<"first";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    return 0;}

代码运行如下：

七、其他

erase(unique(begin( ),end( )), end( )); 对 vector 进行排重

erase(remove(begin( ), end( ), value), end( )); 删除 vector 中值为 value 的元素

sort(begin( ), end( ))// 要加 algorithm 对vector进行从小到大排序，可加cmp 函数 

#include<iostream>#include<vector>#include<algorithm>using namespace std;int main(){    vector<int> myvector;    for(int i=1;i<=10;i++)        myvector.push_back(i);    myvector.push_back(1);    cout<<"first";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    sort(myvector.begin(),myvector.end());    cout<<"second";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    myvector.erase(unique(myvector.begin(),myvector.end()),myvector.end());    cout<<"3rd";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    myvector.erase(remove(myvector.begin(),myvector.end(),1),myvector.end());    cout<<"4th";    for(int i=0;i<myvector.size();i++)        cout<<" "<<myvector[i];    cout<<endl;    return 0;}

代码运行如下：

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