对于动,静态数组使用的一些小思考

对于动,静态数组使用的一些小思考

Zephyr
  2023-06-23 17:00 2023-06-23 17:00 Created   2024-09-17 17:49:52 2024-09-17 17:49:52 Updated   

这次C++练手项目是一个通讯录管理系统，跟着以上B站视频教程（P72-P83）进行开发。
但是，这一次练习解答和我大作业的解答格外相似，但是我用的是vector数组，我立马拿去和上一次大作业的对比，
这引发了我思考——vector动态数组和静态数组到底该如何做选择？
通过这次练习，这个问题得到解答。
如果想查看之前大作业的代码，可以翻阅之前发布的博客文章。

以下是代码

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#include "iostream"
using namespace std;
#define MAX 1000

bool flag = false;
char ch;

struct Person{
    string m_Name;
    string m_Gender;
    int m_Age{};
    string m_Phone;
    string m_Address;
};

struct AddressBook {
    Person personArray[MAX];
    int currentSize{};
};

void menu() {
    cout << "************************************" << endl;
    cout << "*        1. add a new contact       " << endl;
    cout << "*        2. search contact         " << endl;
    cout << "*        3. show all contacts        " << endl;
    cout << "*        4. delete a contact        " << endl;
    cout << "*        5. modify a contact         " << endl;
    cout << "*        6. clean the contact        " << endl;
    cout << "*        0. exit                    " << endl;
    cout << "************************************" << endl;
}

void addPerson(AddressBook *abs){
    system("cls");
    if (abs->currentSize == MAX) {
        cout << "通讯录已满，无法继续添加！" << endl;
        return;
    }else{
        string name;
        cout << "姓名：";
        cin >> name;
        //添加判断，判断输入的姓名是否和数组里所储存的姓名重复
        while (true){
            //每次输入新的姓名之前都要重置 flag.
            //ps:我卡在这很久，想不到输入重复的名字后还得重置 flag，最后还是靠chatGPT才解决的 看来控制流程还得好好学习 :(
            flag = false;
            for (int i = 0; i < abs->currentSize; ++i) {
                if (abs->personArray[i].m_Name == name){
                    flag = true;
                    cout << "姓名重复，请重新输入：";
                    cin >> name;
                    break;
                }
            }if(!flag) {
                abs->personArray[abs->currentSize].m_Name = name;
                break;
            }
        }
        string gender;
        cout << "性别：";
        cin >> gender;
        while (true){
            if (gender == "男" || gender == "女") {   //性别输入约束
                abs->personArray[abs->currentSize].m_Gender = gender;
                break;
            }else  {
                cout << "输入错误，请重新输入性别：" ;
                cin >> gender;
            }
        }
        int age;
        cout << "年龄：";
        cin >> age;
        while(true){
            if (age > 0 && age < 125) {  //年龄区间约束
                abs->personArray[abs->currentSize].m_Age = age;
                break;
            }else{
                cout << "年龄输入区间过于离谱，请重新输入年龄：" ;
                cin >> age;
            }
        }
        string phone;
        cout << "电话号码：";
        cin >> phone;
        abs->personArray[abs->currentSize].m_Phone = phone;
        string Address;
        cout << "地址：";
        cin >> Address;
        abs->personArray[abs->currentSize].m_Address = Address;
        abs->currentSize++;
        system("cls");
        cout << "添加成功！" << endl;
    }
}

void search( AddressBook *abs){
    string name;
    system("cls");
    cout << "请输入要查询的联系人的姓名：";
    cin >> name;
    for (int i = 0; i < abs->currentSize; ++i) {
        if (abs->currentSize == 0){
            cout << "当前通讯录记录为空！" << endl;
        }else{
            if (abs->personArray[i].m_Name == name){
                cout << "姓名：" << abs->personArray[i].m_Name << "\t";
                cout << "性别：" << abs->personArray[i].m_Gender << "\t";
                cout << "年龄：" << abs->personArray[i].m_Age << "\t";
                cout << "电话号码：" << abs->personArray[i].m_Phone << "\t";
                cout << "地址：" << abs->personArray[i].m_Address << endl;
                system("pause");
                system("cls");
                break;
            }else cout << "未找到该联系人！" << endl;
        }
    }
}

void showAll(AddressBook *abs) {
    if (abs->currentSize == 0){
        cout << "当前通讯录记录为空！" << endl;
    }else{
        for (int i = 0; i < abs->currentSize; ++i) {
            cout << "姓名：" << abs->personArray[i].m_Name << "\t";
            cout << "性别：" << abs->personArray[i].m_Gender << "\t";
            cout << "年龄：" << abs->personArray[i].m_Age << "\t";
            cout << "电话号码：" << abs->personArray[i].m_Phone << "\t";
            cout << "地址：" << abs->personArray[i].m_Address << endl;
        }
    }
    system("pause");
    system("cls");
}

void deletePerson(AddressBook *abs){
    string name;
    system("cls");
    cout << "要删除的姓名：";
    cin >> name;
    for(int i = 0; i < abs->currentSize; i++){
        if(abs->personArray[i].m_Name == name){
            flag = true;
            cout << "确认删除？（y/n）";
            cin >> ch;
            if(ch == 'y' || ch == 'Y'){
                for(int j = i; j < abs->currentSize; j++){
                    abs->personArray[j] = abs->personArray[j+1]; //顺序表删除操作
                }
                abs->currentSize--;
                cout << "删除成功！" << endl;
            }else cout << "已取消删除！" << endl;
        }
        if (!flag) cout << "未找到此人！" << endl;
    }
}

void modifyPerson(AddressBook *abs){
    string name;
    int selection;
    system("cls");
    cout << "输入要修改的联系人信息的姓名：";
    cin >> name;
    for (int i = 0; i < abs->currentSize; ++i) {
        if (name == abs->personArray[i].m_Name) {
            flag = true;   //原本课程里需要重新逐一输入信息，比较麻烦，所以这里添加修改选项
            cout << "-----------------------------------------------" << endl;
            cout << "   1.姓名                      2.电话号码        " << endl;
            cout << "   3.性别                      4.年龄          " << endl;
            cout << "   5.地址                      0.返回          " << endl;
            cout << "          请输入相应编号做相应修改。                " << endl;
            cout << "-----------------------------------------------" << endl;
            cin >> selection;
            switch (selection) {
                case 1: {cout << "新的姓名信息："; cin >> abs->personArray[i].m_Name; cout << "修改成功" << endl; break;}
                case 2: {cout << "新的电话号码信息："; cin >> abs->personArray[i].m_Phone; cout << "修改成功" << endl; break;}
                case 3: {cout << "新的性别信息："; cin >> abs->personArray[i].m_Gender; cout << "修改成功" << endl; break;}
                case 4: {cout << "新的年龄信息："; cin >> abs->personArray[i].m_Age; cout << "修改成功" << endl; break;}
                case 5: {cout << "新的地址信息："; cin >> abs->personArray[i].m_Address; cout << "修改成功" << endl; break;}
                case 0: system("cls"); return;
                default:cout << "输入错误！" << endl; break;
            }
        }
    }if (!flag) cout << "查无此人！" << endl;
}

void cleanAll(AddressBook *abs) {
    cout << "确认全部清除？（y/n）";
    cin >> ch;
    if(ch == 'y' || ch == 'Y'){
        for (int i = 0; i < abs->currentSize; ++i) {
            abs->personArray[i].m_Name.clear();
            abs->personArray[i].m_Gender.clear();
            abs->personArray[i].m_Age = 0;
            abs->personArray[i].m_Phone.clear();
            abs->personArray[i].m_Address.clear();
            abs->currentSize = 0;
        }
        cout << "所有联系人信息均已消除！" << endl;
    }else cout << "删除取消！" << endl;
}

int main()
{
    AddressBook abs;
    abs.currentSize = 0;
    while(true){
        menu();
        int selection = 0;
        cin >> selection;
        switch (selection) {
            case 1: addPerson(&abs);
                break;
            case 2: search(&abs);
                break;
            case 3: showAll(&abs);
                break;
            case 4: deletePerson(&abs);
                break;
            case 5: modifyPerson(&abs);
                break;
            case 6: cleanAll(&abs);
                break;
            case 0: cout <<  "Bye!" << endl; exit(0);
            default: cout << "Input Error! Please input a valid number." << endl;
                break;
        }
    }
}

下面是将静态数组换成vector动态数组的码子

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#include "iostream"
#include "vector"
using namespace std;
#define MAX 1000

bool flag = false;
char ch;

struct Person{
    string m_Name;
    string m_Gender;
    int m_Age{};
    string m_Phone;
    string m_Address;
};
vector<Person> persons;
void menu() {
    cout << "************************************" << endl;
    cout << "*        1. add a new contact       " << endl;
    cout << "*        2. search contact         " << endl;
    cout << "*        3. show all contacts        " << endl;
    cout << "*        4. delete a contact        " << endl;
    cout << "*        5. modify a contact         " << endl;
    cout << "*        6. clean the contact        " << endl;
    cout << "*        0. exit                    " << endl;
    cout << "************************************" << endl;
}

void addPerson(){
    Person person;
    system("cls");
    if (persons.size() == MAX) {
        cout << "通讯录已满，无法继续添加！" << endl;
        return;
    }else{
        string name;
        cout << "姓名：";
        cin >> name;
        while (true){
            flag = false;
            for (int i = 0; i < persons.size(); ++i) {
                if (person.m_Name == name){
                    flag = true;
                    cout << "姓名重复，请重新输入：";
                    cin >> name;
                    break;
                }
            }if(!flag) {
                person.m_Name = name;
                break;
            }
        }
        string gender;
        cout << "性别：";
        cin >> gender;
        while (true){
            if (gender == "男" || gender == "女") {  
                person.m_Gender = gender;
                break;
            }else  {
                cout << "输入错误，请重新输入性别：" ;
                cin >> gender;
            }
        }
        int age;
        cout << "年龄：";
        cin >> age;
        while(true){
            if (age > 0 && age < 125) {  
                person.m_Age = age;
                break;
            }else{
                cout << "年龄输入区间过于离谱，请重新输入年龄：" ;
                cin >> age;
            }
        }
        string phone;
        cout << "电话号码：";
        cin >> phone;
        person.m_Phone = phone;
        string Address;
        cout << "地址：";
        cin >> Address;
        person.m_Address = Address;
        persons.push_back(person);
        system("cls");
        cout << "添加成功！" << endl;
    }
}

void search(){
    string name;
    system("cls");
    cout << "请输入要查询的联系人的姓名：";
    cin >> name;
    for (const auto& person : persons) {
        if (persons.empty()){
            cout << "当前通讯录记录为空！" << endl;
        }else{
            if (person.m_Name == name){
                cout << "姓名：" << person.m_Name << "\t";
                cout << "性别：" << person.m_Gender << "\t";
                cout << "年龄：" << person.m_Age << "\t";
                cout << "电话号码：" << person.m_Phone << "\t";
                cout << "地址：" << person.m_Address << endl;
                system("pause");
                system("cls");
                break;
            }else cout << "未找到该联系人！" << endl;
        }
    }
}

void showAll() {
    if (persons.empty()){
        cout << "当前通讯录记录为空！" << endl;
    }else{
        for (const auto& person : persons) {
            cout << "姓名：" << person.m_Name << "\t";
            cout << "性别：" << person.m_Gender << "\t";
            cout << "年龄：" << person.m_Age << "\t";
            cout << "电话号码：" << person.m_Phone << "\t";
            cout << "地址：" << person.m_Address << endl;
        }
    }
    system("pause");
    system("cls");
}

void deletePerson(){
    string name;
    system("cls");
    cout << "要删除的姓名：";
    cin >> name;
    for(int i = 0; i < persons.size(); i++){
        if(persons[i].m_Name == name){
            flag = true;
            cout << "确认删除？（y/n）";
            cin >> ch;
            if(ch == 'y' || ch == 'Y'){
                persons.erase(persons.begin() + i);
                cout << "删除成功！" << endl;
            }else cout << "已取消删除！" << endl;
        }
        if (!flag) cout << "未找到此人！" << endl;
    }
}

void modifyPerson(){
    string name;
    int selection;
    system("cls");
    cout << "输入要修改的联系人信息的姓名：";
    cin >> name;
    for (auto &person : persons) {
        if (name == person.m_Name) {
            flag = true;   
            cout << "-----------------------------------------------" << endl;
            cout << "   1.姓名                      2.电话号码        " << endl;
            cout << "   3.性别                      4.年龄          " << endl;
            cout << "   5.地址                      0.返回          " << endl;
            cout << "          请输入相应编号做相应修改。                " << endl;
            cout << "-----------------------------------------------" << endl;
            cin >> selection;
            switch (selection) {
                case 1: {cout << "新的姓名信息："; cin >> person.m_Name; cout << "修改成功" << endl; break;}
                case 2: {cout << "新的电话号码信息："; cin >> person.m_Phone; cout << "修改成功" << endl; break;}
                case 3: {cout << "新的性别信息："; cin >> person.m_Gender; cout << "修改成功" << endl; break;}
                case 4: {cout << "新的年龄信息："; cin >> person.m_Age; cout << "修改成功" << endl; break;}
                case 5: {cout << "新的地址信息："; cin >> person.m_Address; cout << "修改成功" << endl; break;}
                case 0: system("cls"); return;
                default:cout << "输入错误！" << endl; break;
            }
        }
    }if (!flag) cout << "查无此人！" << endl;
}

void cleanAll() {
    cout << "确认全部清除？（y/n）";
    cin >> ch;
    if(ch == 'y' || ch == 'Y'){
        persons.clear();
        cout << "所有联系人信息均已消除！" << endl;
    }else cout << "删除取消！" << endl;
}

int main()
{
    while(true){
        menu();
        int selection = 0;
        cin >> selection;
        switch (selection) {
            case 1: addPerson();
                break;
            case 2: search();
                break;
            case 3: showAll();
                break;
            case 4: deletePerson();
                break;
            case 5: modifyPerson();
                break;
            case 6: cleanAll();
                break;
            case 0: cout <<  "Bye!" << endl; exit(0);
            default: cout << "Input Error! Please input a valid number." << endl;
                break;
        }
    }
}

静态数组和vector动态数组各有千秋：

​ Vector动态数组：

  1. 动态大小：Vector 是一个动态容器，可以根据需要在运行时调整大小。它能够自动处理内存管理和扩展，而无需显式指定初始大小（与静态数组不同）。这使得 Vector 更加灵活，能够适应动态的数据需求。

  2. 安全性：Vector 具有边界检查功能，可以确保访问元素时不会越界，减少了程序崩溃或发生其他错误的风险。而静态数组没有内置的边界检查机制，如果不小心越界访问，可能会导致未定义的行为。

  3. 方便的操作和函数：Vector 对象提供了方便的成员函数和算法，如插入、删除、排序等操作。而静态数组通常需要手动编写这些操作的代码，相对来说更加繁琐。

  4. 可以返回长度：Vector 有 size() 成员函数用于获取当前容器中元素的数量，而对于静态数组，需要使用额外变量或固定长度进行追踪。

  5. 可以作为函数参数和返回值：Vector 可以直接作为函数的参数和返回值传递，而静态数组传递时需要指定数组大小，且容易造成内存浪费或限制传递的数组大小。

​ 静态数组：

  1. 内存效率：静态数组在编译时就分配了连续的内存空间，并且没有额外的运行时开销。这使得静态数组在内存访问方面更加紧凑和高效，能够提高数据访问的局部性和缓存命中率，从而提升访问性能。
  2. 简单和直观：静态数组是一种基本的数据结构，使用起来非常简单和直观。只需声明数组并指定大小，即可直接访问和操作数组元素。
  3. 编译时确定大小：静态数组的大小在编译时确定，无法动态改变。这可以作为一种约束，确保不会超出预期的数组范围，并在编译时发现潜在的错误。
  4. 不涉及动态内存管理：由于静态数组在编译时分配了固定大小的内存，因此不存在动态内存管理的问题。这样可以避免动态内存分配和释放带来的开销和内存碎片问题。
  5. 适用于小规模数据集：对于小规模的数据集，静态数组的性能优势通常是微不足道的。与 Vector 数组相比，静态数组可能具有更低的内存开销和更高的执行效率。

在选择使用静态数组还是 Vector 数组时，需要综合考虑具体场景、数据规模和操作需求，并权衡各自的优缺点。

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对于动,静态数组使用的一些小思考