Question

C++基础问题 vector复制给数组

#include <iostream>
#include <vector>
using namespace std;

// 编写程序把int 型vector 复制给int 型数组。
int main()
{
int word;
vector<int> num;
while(cin >> word){
num.push_back(word);
}

int len = num.size();
int *pt = new int[len];
size_t ix=0;
for (vector<int>::iterator iter=num.begin();iter!=num.end();++iter,++pt,++ix)
{
pt[ix] = *iter;
cout<<*pt<<" "<<*iter<<" "<<pt[ix]<<" | ";
}

delete [] pt;
return 0;
}

请问如果输入1 2 3 x
*pt的输出为何不是 1 2 3？

Answer 1

//pt[ix]和pt++一起用导致的错误,应用另一个指针保存首地址
#include <iostream>
#include <vector>
using namespace std;// 编写程序把int 型vector 复制给int 型数组。
int main()
{
int word;
vector<int> num;
while(cin >> word){
num.push_back(word);
}int len = num.size();
int *pt = new int[len],*p=pt;
size_t ix=0;
for (vector<int>::iterator iter=num.begin();iter!=num.end();++iter,++p,++ix)
{
pt[ix] = *iter;
cout<<*p<<" "<<*iter<<" "<<pt[ix]<<" | ";
}delete [] pt;
return 0;
}