将输入存储到Arrays C ++中

Question

I am learning about arrays , what I wanted to try is first let the user enter x,y values 4 times eg

first time

x = 1
y = 3

second time

 x = 2
 y = 3

third time

 x = 3
 y = 1

fourth time

 x = 1
 y = 3

. and then store the value that the user had key in 4 times inside a array and print them out but I getting some weird outputs.

my output

10001711642800 <-- some weird output

expected output

1,3
2,3
3,1
1,3

code(not working)

      int x;
      int y;

     //request the user to enter x and y value 4 times.
     for (int i=1; i<5; i++) {
        cout << i << "Please enter x-cord." << endl;
        cin >> x;

        cout <<i << "Please enter y-cord." << endl;
        cin >> y;
    }
     //intitalize the array size and store the x,y values   
    int numbers[4][4] = { 
        x, y
    };
    //loop through 4 times to print the values.
    for (int i = 0; i<5; i++) {
        cout << numbers[i][i];
    }

I know it can be done with vectors but now I am trying with arrays because I am weak in using arrays.

Answer 1

You are confusing a lot of things here.

1. In your for -loop you are overwriting the value stored in x and y at each iteration of the loop.
2. int numbers[4][4] creates a two-dimensional array containing a total of 16 elements. What you want is int numbers[4][2] .
3. Your array initialization is incomplete, because x and y only contain the last two values the user has entered, not all 8.

To fix this, you should create the array before the for -loop and then store the values the user enters directly into the array.

Answer 2

use this code:

int numbers[4][2];
for(int i=0;i<4;i++)
{
   cout<<i<<": Please enter x-cord."<<endl;
   cin>>numbers[i][0];
   cout<<i<<": Please enter y-cord."<<endl;
   cin>>numbers[i][1];
}

for (int i = 0; i<4; i++) 
{
        cout << numbers[i][0]<<"   "<<numbers[i][1];
}

Answer 3

You're not storing the input received from the user in any array. They're overwritten again and again in the loop. Store them in an array and then display it.

 //intitalize the array size and store the x,y values   
int numbers[4][4] = { 
    x, y
};

This is not required. Since you're going to overwrite the contents of the array you needn't initialize them with some random variables. In fact the variables x and y are not at all required.

#include <iostream>

int main(int argc, char *argv[])
{
    // you need 4 arrays of 2 numbers, not 4x4 but 4x2
    int numbers[4][2] = { { } };        // initialize all of them to 0
    for (size_t i = 0; i < 4; ++i)
    {
        std::cout << "x = ";
        std::cin >> numbers[i][0];      // store the input directly in the array
        std::cout << "y = ";            // instead of using a dummy
        std::cin >> numbers[i][1];
    }

    // display array contents
    for (size_t i = 0; i < 4; ++i)
    {
        std::cout << numbers[i][0] << ", " << numbers[i][1] << std::endl;
    }
}

Answer 4

First, you have to declare the variable you need to fill;

 // A new data type which holds two integers, x and y
 struct xy_pair {
     int x;
     int y;
 };

 // A new array of four xy_pair structs
 struct xy_pair numbers[4];

Then, you can begin filling it.

 //request the user to enter x and y value 4 times.
 for (int i=1; i<5; i++) {
    cout << i << "Please enter x-cord." << endl;
    cin >> numbers[i].x;

    cout <<i << "Please enter y-cord." << endl;
    cin >> numbers[i].y;
}

Then, you can print it!

//loop through 4 times to print the values.
for (int i = 0; i<5; i++) {
    cout << "X is " << numbers[i].x << " and Y is " << numbers[i].y << endl;
}

PS! I haven't run the code myself, let me know if it doesn't work.