順序容器操作2
容器插入
list<string>::iterator iter = slist.begin();
++iter;
++iter;
iter = slist.insert(iter, "----");//插入1
cout << *iter << endl;
for(list<string>::iterator i = slist.begin();
i != slist.end(); ++i)
cout << *i << " ";
cout << endl;
string sarray[4 ] = {"queke","hanliang","lexm", "kitty"};
slist.insert(slist.end(), sarray+1, sarray+3); //插入2
for(list<string>::iterator i = slist.begin();
i != slist.end(); ++i)
cout << *i << " ";
cout << endl;
slist.insert(slist.begin(), 4, "hello"); //插入3
for(list<string>::iterator i = slist.begin();
i != slist.end(); ++i)
cout << *i << " ";
cout << endl;
1- slist.insert(iter, key)在迭代器iter位置插入元素key,返回插入元素key的位置
2-slist.insert(iter, iter1, iter2)在迭代器iter所指示位置,插入迭代器範圍[iter1,iter2)之間的元素副本,範圍void
3-slist.insert(iter, n, key)在迭代器iter位置處插入n個值為key的元素,範圍void
注意:新增元素會使原來迭代器失效,所以需要更新的容器的迭代器也要更新,如下:
vector <string>::iterator ibeg = a.begin();
vector<string>::iterator iend = a.end();
while(ibeg != iend){ //錯誤,iend失效
a.insert(ibeg, "hello");
++ibeg;
}
vector<string>::iterator ibeg = a.begin();
while(ibeg != a.end()){ //正確每次重新取容器最後邊界
ibeg = a.insert(++ibeg, "hello");
++ibeg;//略過當前插入的元素,取下一個
}
容器大小操作
#include<iostream>
#include<vector>
#include<list>
#include<deque>
using namespace std;
int main()
{
list<int> ilist;
ilist.push_back(10);
ilist.push_back(20);
ilist.push_back(30);
cout << "number of list:" << ilist.size() << endl;
list<int>::size_type sum = ilist.size();
cout << "number of list: " << ilist.size() << endl;
cout << "max size of list: " << ilist.max_size() << endl;
if(ilist.empty())
cout << "list is empty ! " << endl;
else
cout << "list is not empty" << endl;
ilist.resize(10);//調整容器大小有10個數,多增加的7個預設為0;
for(list<int>::iterator iter = ilist.begin();
iter != ilist.end(); ++iter)
cout << *iter << " ";
cout << endl;
ilist.resize(20, -1); //調整容器大小變為20個,預設多增加的都為-1;
for(list<int>::iterator iter = ilist.begin();
iter != ilist.end(); ++iter)
cout << *iter << " ";
cout << endl;
ilist.resize(2);//容器縮小了
for(list<int>::iterator iter = ilist.begin();
iter != ilist.end(); ++iter)
cout << *iter << " ";
cout << endl;
ilist.resize(0);
if(ilist.empty())
cout << "list is empty ! " << endl;
else
cout << "list is not empty" << endl;
vector<int> ivec(10, 42); //10個42;
ivec.resize(15);
ivec.resize(25, -1);
ivec.resize(5);
return 0;
}
a.size() 容器的大小,返回size_type
a.max_size(); 容器最大能容納的數量,返回size_type
a.empty(); 判斷容器為空
a.resize(n);重置容器大小
a.resize(n, default);重置容器大小,新新增的元素值都為default
注意:resize可能使迭代器失效,適用vector,list, deque
容器訪問
vector<int> ivec;
ivec.push_back(10);
ivec.push_back(20);
ivec.push_back(30);
cout << ivec.front() << endl;//第一個元素,10
cout << ivec.back() << endl;//最後一個元素,30
vector<int>::reference a = ivec.front();//返回引用
vector<int>::reference b = ivec.back();//返回引用
cout << a << endl;
cout << b << endl;
cout << *ivec.begin() << endl;//迭代器訪問第一個元素,10
cout << *(--ivec.end()) << endl;//迭代器訪問最後元素,30
vector<int>::reference c = *ivec.begin();//迭代器也可以返回引用
vector<int>::reference d = *--ivec.end();
cout << c << endl;
cout << d << endl;
cout << ivec[0] << endl;//下標訪問
cout << ivec[1] << endl;
cout << ivec[2] << endl;
cout << ivec[300] << endl; //越界,嚴重錯誤,只能終止程式
cout << ivec.at(0) << endl;//at(n)下標訪問
cout << ivec.at(1) << endl;
cout << ivec.at(2) << endl;
try {
cout << ivec.at(300)<< endl; //越界,丟擲異常,可以用try捕獲
}catch(out_of_range){
cout << "出錯,下標越界!" << endl;
}
list<int> ilist;
if(!ilist.empty())
{
cout << ilist.front() << endl;
cout << ilist.back() << endl;
}
//cout << ilist[0] << endl; 連結串列沒有下標,不能用下標訪問
//cout << ilist.at(0) << endl;
注意:vector , deque有下標訪問,list沒有
容器刪除
c.erase(iter);刪除迭代器iter指向的元素,返回被刪除元素的後面一個元素迭代器
c.erase(iter1, iter2);刪除迭代器範圍內的元素,返回刪除的後面一個元素迭代器
c.clear();清除所有容器,返回void
c.pop_back();刪除最後一個,返回void
c.pop_front();刪除第一個,返回void,適用於deque和list
容器賦值和交換
c1 = c2 容器賦值,型別必須相同
vector<int> ivec1;
vector<int> ivec2;
ivec1.push_back(10);
ivec1.push_back(20);
ivec1.push_back(30);
ivec2 = ivec1;
for(vector<int>::iterator iter = ivec2.begin();
iter != ivec2.end(); ++iter)
cout << *iter << " "; //10,20,30
c1.swap(c2) c1和c2交換元素,元素型別相同
vector<int> ivec1;//10,20,30
vector<int> ivec2;//1,2,3,4
ivec1.push_back(10);
ivec1.push_back(20);
ivec1.push_back(30);
ivec2.push_back(1);
ivec2.push_back(2);
ivec2.push_back(3);
ivec2.push_back(4);
ivec2.swap(ivec1);//ivec2-10,20,30;ivec1-1,2,3,4
c.assign(iter1, iter2)將迭代器範圍內元素複製到c中,元素型別相容,容器型別可以不同
ivec2.assign(++ivec1.begin(), ivec1.end());
for(vector<int>::iterator iter = ivec2.begin();
iter != ivec2.end(); ++iter)
cout << *iter << " ";//20,30
c.assign(n,key) 將容器重新設定儲存n個值為key的元素