如何调用数组中的值并更改数组中的值？

Question

class DataStorage{
                        // 0 1 2 3 4        5 6 7 8
string Data[20][4]={{"Wee","50","1","First"},{"Wee","22","2","First"},
                        // 9 10 11 12       13 14 15 16
                    {"Jason","26","3","First"},{"Krappa","12","4","First"},
                        // 17 18 19 20      21 22 23 24
                    {" "," ","5","First"},{" "," ","6","Economy"},
                        //25 26 27 28       29 30 31 32
                    {"Kappa","15","7","Economy"},{"Eraser","17","8","Economy"},
                        //33 34 35 36       37 38 39 40
                    {" "," ","9","Economy"},{"Morty"," ","10","Economy"},
                        //41 42 43 44       45 46 47 48
                    {"Rick"," ","11","Economy"},{"Amanda","10","12","Economy"},
                        //49 50 51 52       53 54 55 56
                    {"Lee","","13","Economy"},{"MingLee"," ","14","Economy"},
                        //57 58 59 60       61 62 63 64
                    {"Beauty"," ","15","Economy"},{"S4head"," ","16","Economy"},
                        //65 66 67 68       69 70 71 72
                    {"Ivan"," ","17","Economy"},{"Dex"," ","18","Economy"},
                        //73 74 75 76       77 78 79 80
                    {"Chua"," ","19","Economy"},{"Haha"," ","20","Economy"},};
};
int main(){

}

How do I call the value in array and change the value in array? Do I need to make some function to get value from the input and pass it into a variable in class and set it into my array?

Answer 1

I'm not sure what you're asking when you say How do I call the value in array and change the value in array? but I think you're asking how do you change the value of an array element.

To modify an array element you assign the array's index to what you're changing the array's element to; however, remember that C++ arrays are 0-index arrays meaning when you start counting their elements at 0. For example the following code modifies the element at index 5. Live preview

#include <iostream>

int array[10] = {1, 5, 33, 7, -23, 2, 8, 54, 19, 2};

int main() {
  std::cout << array[5] << std::endl;

  array[5] = 100; // Set the value of the element at index 5 to 100

  std::cout << array[5] << std::endl;

  return 0;
}

Answer 2

If you want to have Data as a class member of DataStorage you have to initialize it in the member initialization list. I also highly recommend to use an abstraction for the bare array, like std::array . This allows to use bounds-checked access with the at() function. You can then access Data and change it's contents.

#include <array>
#include <iostream>
#include <string>

class DataStorage
{
public:
    std::array<std::array<std::string,4>,20> Data;
    DataStorage() : Data({{
                {{"Wee","50","1","First"}},
                {{"Wee","22","2","First"}},
                {{"Jason","26","3","First"}},
                {{"Krappa","12","4","First"}},
                {{" "," ","5","First"}},
                {{" "," ","6","Economy"}},
                {{"Kappa","15","7","Economy"}},
                {{"Eraser","17","8","Economy"}},
                {{" "," ","9","Economy"}},
                {{"Morty"," ","10","Economy"}},
                {{"Rick"," ","11","Economy"}},
                {{"Amanda","10","12","Economy"}},
                {{"Lee","","13","Economy"}},
                {{"MingLee"," ","14","Economy"}},
                {{"Beauty"," ","15","Economy"}},
                {{"S4head"," ","16","Economy"}},
                {{"Ivan"," ","17","Economy"}},
                {{"Dex"," ","18","Economy"}},
                {{"Chua"," ","19","Economy"}},
                {{"Haha"," ","20","Economy"}}
            }}) {}
};

int main()
{
    DataStorage d;
    std::cout << d.Data.at(10).at(2) << '\n'; // prints 11
    d.Data.at(10).at(2) = "1729";
    std::cout << d.Data.at(10).at(2) << '\n'; // prints 1729
}