C++ 拉取信息并循环显示

Question

不在数组的常设循环之下。循环遍历所有抓取或搜索。有人可以解释这个过程吗？提前致谢。对不起，如果重复。我环顾四周，找不到我能理解的可靠解释。

#include <fstream>
#include <iostream>
#include <string>
#include <cstring>

using namespace std;

void allContacts(string names[], string phones[])
{
    cout << "Showing all contacts... Press Q to go back to main menu" << endl;
}

void addName(string names[], string phones[])
{
    bool keepGoing;
    string input;

    beginning:
    for (int i = 0; i < sizeof(names); i++)
    {
        cout << "Enter contact name: ";
        cin >> names[i];
        cout << "Enter contact number: ";
        cin >> phones[i];
        cout << "Do you have another contact to add? y or no" << endl;
        cin >> input;
        if(input == "y" || input == "Y")
        {
            goto beginning;
        }

        if(input == "n" || input == "N")
        {
            cout << "Contacts you have entered: " << endl;
            cout << names[i] << " : " << phones[i] << endl;
        }
    }
}

void searchName(string names[], string phones[])
{
    string name;
    cout << "Enter Name: ";
    cin >> name;

    cout << "Search for a name or Press Q to go back to main menu" << endl;

    for (int i = 0; i < sizeof(names); i++){
        if (name == names[i])
        {
            cout << counter << names[i] << " 's phone number is: " << phones[i] << endl;
        } else {
            cout << "No results found";
        }
    }
}

int main()
{
    string names[100];
    string phones[100];
    int choice;

    cout << "============================" << endl;
    cout << "=== Welcome to PhoneBook ===" << endl;
    cout << "============================" << endl;

    cout << "1- Add a New Contact" << endl;
    cout << "2- Search By Name" << endl;
    cout << "3- Display All" << endl;
    cout << "0- Exit" << endl;

    cout << "Select a number: " << endl;
    cin >> choice;

    switch(choice)
    {
    case 1:
        addName(names, phones);
        break;
    case 2:
        searchName(names, phones);
        break;
    case 3:
        allContacts(names, phones);
        break;
    case 0:
        cout << "Exiting PhoneBook...";
            break;
    }
}

Answer 1

在 C++ 中，数组在传递给函数时会丢失属性。这些属性是容量和大小(已填充插槽的数量)。您需要为每个数组传递此附加信息:

void addName(string names[],  unsigned int names_capacity, unsigned int names_size,
 string phones[], unsigned int phones_capacity, unsigned int phones_size)

要解决这个问题，您可以使用 std::vector。 std::vector 知道它的容量和大小，因此您不必将额外的属性传递给您的函数。

另外，如果你在比较之前使用tolower或toupper，你只需要进行一次比较:

char input; 
cout << "Do you have another contact to add? y or n" << endl;
cin >> input;
input = toupper(input);
if(input == 'Y')

在使用字符串时，可以通过std::transform将其全部转为大写或全部转为小写，如:

  std::transform(input.begin(),
                 input.begin(), input.end(),
                 tolower);