Adding columns to a 2-D array

Question

Any desired array entered by the user , code look for every column , if any element in any column is equal to number y.Then the code should add a new column of zeros in front of it.

Code

#include <pch.h>
#include <iostream>

using namespace std;

int main()
{
int y, rows, columns;
std::cout << "Enter the number of rows: ";
std::cin >> rows;
std::cout << "Enter the number of columns: ";
std::cin >> columns;
std::cout << "Enter a number Y: ";
std::cin >> y;

//-----------------------Generating 2-D array---------------------------------------------------------
int **array = new int*[2 * rows];
for (int i = 0; i < rows; i++)
    array[i] = new int[columns];
//------------------------Generating bool--------------------------------------------------------------
bool *arrx = new bool[columns];
//-----------------------Input Array Elements---------------------------------------------------------
std::cout << "Enter the elements" << std::endl;
for (int i = 0; i < columns; i++)
    for (int j = 0; j < rows; j++)
        std::cin >> array[i][j];
//--------------------Loop for the array output--------------------------------------------------------
for (int i = 0; i < columns; i++) {
    for (int j = 0; j < rows; j++) {
        std::cout << array[i][j] << " ";
    }
    std::cout << "\n";
}
//-------------------Loop for finding columns with even numbers----------------------------------------
for (int i = 0; i < columns; i++) {
    arrx[i] = false;
    for (int j = 0; j < rows; j++) {
        if (array[j][i] == y) {
            arrx[i] = true;
        }
    }
}
std::cout << "\n";
//--------------------Loop for addition of new columns infront of even numbers--------------------------
for (int i = 0; i < columns; i++) {
    for (int j = 0; j < rows; j++) {
        std::cout << array[i][j] << " ";
    }
    std::cout << "\n";
    if (arrx[i]) {
        for (int i = 0; i < rows; i++) {
            std::cout << 0 << " ";
        }
        std::cout << "\n";
    }
}

return 0;
}

Here this code adds only rows to the array while I need to add columns . I have tried changing array[i][j] to array[j][i] but in vain.

Because this is the last manual task , of adding and removing elements in our course . The next topic we are going to start is std::vector — J.Doe
– J.Doe, Commented Nov 20, 2018 at 13:37
please add such requirements to the question. Homework assignments often come with rather strange constraints, eg in real life no sane c++ coder would use manually allocated arrays for that task — 463035818_is_not_an_ai
– 463035818_is_not_an_ai, Commented Nov 20, 2018 at 13:40

Hristijan Gjorshevski · Accepted Answer · 2018-11-20 13:34:35Z

2

You need to replace

for (int i = 0; i < columns; i++) {
    for (int j = 0; j < rows; j++) {
        std::cout << array[i][j] << " ";
    }
    std::cout << "\n";
    if (arrx[i]) {
        for (int i = 0; i < rows; i++) {
            std::cout << 0 << " ";
        }
        std::cout << "\n";
    }
}

with

for (int i = 0; i < rows; i++) {
    for (int j = 0; j < columns; j++) {
        std::cout << array[i][j] << " ";
        if (arrx[j]) {
           std::cout << 0 << " ";
         }
    }
}

This prints a zero after every element whose column value is marked. What you were trying to do is print to standard output column by column which is not how it works.

Also I urge you to consider using a std::vector instead of plain pointers to avoid errors like here where you have forgotten to deallocate your memory.

edited Nov 20, 2018 at 13:34

answered Nov 20, 2018 at 13:29

Hristijan Gjorshevski

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1 Comment

J.Doe Over a year ago

And should I change all the arrx[i] to arrx[j] ?

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