Input not accepted

[Arez]

#include <iostream>
using namespace std;

#define height 3
#define width 5

int arr[height][width];
int n,m;

int main ()
{
    do {
        cout << "Enter n: ";
        cin >> n;
        cout << "Now m: ";
        cin >> m;
    for (n=0; n<height; n++)
     for (m=0; m<width; m++)
     {
         arr[n][m]=(n+1)*(m+1);
     }
     cout << arr[n][m] << "\n";
     } while (n != 2);
     return 0;
}

what's wrong??

[GuOddian]

The problem you have is in the loops. In the loop:

for (n=0; n<height; n++)

the n=0 sets n equal to 0 therefore ignoring the input entirely. The same goes for the for loop with m as the subject.

Try removing the for loops entirely and see what response you get from the code, I.E.

int main ()
{
    do {
        cout << "Enter n: ";
        cin >> n;
        cout << "Now m: ";
        cin >> m;
        arr[n][m]=(n+1)*(m+1);
        cout << arr[n][m] << "\n";
     } while (n != 2);
     
     return 0;
}

[[email protected]]

what's wrong??

Look at:

     cout << arr[n][m] << "\n";

Because this line will be executed after n-loop block, then it should be
arr[height][width] => arr[3][5]....this causes memory fault.

In this line:

     } while (n != 2);

at this point n will always be 3, and then the while loop will never end.

[edijs.vee]

and the first for loop has no brackets which would define its block.

[treuss]

and the first for loop has no brackets which would define its block.

The scope of the outer for-loop is the next statement, i.e. the inner for-loop. No problem there except one could call this bad style.

[nitin1979]

code with correction

#include <iostream>
using namespace std;

const  int HEIGHT = 3;  // use const instead of #define
const  int WIDTH = 5; // always use capital letter for constant

//int arr[height][width];  why you take them global variable
//int n,m;                        why global

int main ()
{
    int arr[HEIGHT][WIDTH];
    int n,m;
    do
    {
        cout << "Enter n: ";
        cin >> n;
        cout << "Now m: ";
        cin >> m;
     //for(n=0; n<height; n++) why you are changing value of n and m
     //for (m=0; m<width; m++)
     //Always use braces to define scope
     for(int i=0;i<HEIGHT;i++)
     {
         for(int j=0;j<WIDTH;j++)
            arr[i][j]=(i+1)*(j+1);
         cout << arr[i][i] << "\n";
     }//For end
     } while (n != 2);
     return (1);
}

Regards

[treuss]

code with correction

Hard to correct code, if the OP does not tell us what m and n should be used for Your program creates the same array again and again until the user enters 2 for n. Is there a deep sense behind this?

Some comments:

#include <iostream>
using namespace std;

const  int HEIGHT = 3;  // use const instead of #define
const  int WIDTH = 5; // always use capital letter for constant

//int arr[height][width];  why you take them global variable
//int n,m;                        why global

int main ()
{
    int arr[HEIGHT][WIDTH];
    int n,m;
    do
    {
        cout << "Enter n: ";
        cin >> n;
        cout << "Now m: ";
        cin >> m; // m is never used below
     //for(n=0; n<height; n++) why you are changing value of n and m
     //for (m=0; m<width; m++)
     //Always use braces to define scope // so why don't you below?
     for(int i=0;i<HEIGHT;i++)
     {
         for(int j=0;j<WIDTH;j++)
            arr[i][j]=(i+1)*(j+1); // where are n and m ?
         cout << arr[i][i] << "\n"; // arr[3][3] is not a valid array member!
     }//For end
     } while (n != 2); // should be while (n != 42)
     return (1); // why? Did the program fail ?
}