12.6 使用动态分配的vector<int>输入和打印vector

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本文介绍了一个使用C++实现的控制台应用程序，该程序通过智能指针管理和操作动态分配的向量，包括创建、读取和输出元素。演示了如何使用shared_ptr来替代裸指针，提高内存安全性和资源管理效率。

// Demo.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <vector>


using namespace std;

vector<int> *create(vector<int>::size_type i) {
   return new (nothrow) vector<int>(i);
}

vector<int> *read(vector<int> *vp) {
   cout << "Please enter the elements" << endl;
   size_t times = vp->size();
   int tmp;
   for (int i = 0; i < times; ++i) {
      cin >> tmp;
      (*vp)[i] = tmp;
   }
   return vp;
}

void output(vector<int> *vp) {
   cout << "Output the elements" << endl;
   size_t times = vp->size();
   for (int i = 0; i < times; ++i) {
      cout << (*vp)[i] << " ";
   }
   cout << endl;
}

int main()
{
   cout << "Please enter the vector size" << endl;
   size_t vectorSize;
   cin >> vectorSize;
   vector<int> *vp = create(vectorSize);
   output(read(vp));
   delete vp;
   vp = nullptr;

   return 0;
}

使用智能指针：

shared_ptr<vector<int>> create(vector<int>::size_type i) {
   return make_shared<vector<int>>(i);
}

shared_ptr<vector<int>> read(shared_ptr<vector<int>> vp) {
   cout << "Please enter the elements" << endl;
   size_t times = vp->size();
   int tmp;
   for (int i = 0; i < times; ++i) {
      cin >> tmp;
      (*vp)[i] = tmp;
   }
   return vp;
}

void output(shared_ptr<vector<int>> vp) {
   cout << "Output the elements" << endl;
   size_t times = vp->size();
   for (int i = 0; i < times; ++i) {
      cout << (*vp)[i] << " ";
   }
   cout << endl;
}

int main()
{
   cout << "Please enter the vector size" << endl;
   size_t vectorSize;
   cin >> vectorSize;
   shared_ptr<vector<int>> vp = create(vectorSize);
   output(read(vp));

   return 0;
}