C 2D array, problem outputting more columns-CodePudding

How come no matter what I do for rows and columns my columns won't go above two? It should be 8x8 adding the 8 numbers together 8 times. I don't know what I'm doing wrong. Thank you

#include <iostream>
#include <iomanip>
#include <cstdlib>

using namespace std;

int main() {
    srand(time(0));
    
    int array1[8][8];
    int array2[8][8];
    int addition[8][8];
    
    for (int i = 0; i < 7; i  ) {
        for (int j = 0; j < 7; j  )
        array1[i][j] = rand() % 6;
    }
    for (int i = 0;i < 7; i  ) {
        for (int j = 0; j < 7; j  ) {
            array2[i][j] = rand() % 8;
        }
    }
    {
        for (int i = 0; i < 7; i  ) {
            for (int j = 0; j < 7; j  ) {
                addition[i][j] = array1[i][j]   array2[i][j];
            }
            for (int i = 0; i < 7; i  ) {
                for (int j = 0; j < 7; j  ) {
                    cout << array1[i][j];
                    cout << "  " << array2[i][j];
                    cout << "  " << endl;
                    cout << "both previous numbers added together = " << addition[i][j] << endl;
                }
            }
            return 0;
        }
    }
}

CodePudding user response：

Hi look carefully at the code structure. you had some extra brackets. This is the correct structure:

#include <iostream>

//using namespace std; - use this only in simple projects (my opinion).

int main()
{ 
    srand(time(0));

    int array1[8][8];
    int array2 [8][8];
    int addition[8][8];

    for (int i = 0;i < 8;i  )
    {
        for (int j = 0; j< 8;j  )
        array1[i][j] = rand() % 6;
    }   

    for (int i = 0;i < 8;i  )
    {
        for (int j = 0;j < 8;j  )
        array2[i][j] = rand() % 8;
    }
   //{ - you dont need this here
    for (int i = 0;i < 8;i  )
    {
        for (int j = 0;j < 8;j  )
            addition[i][j] = array1[i][j]   array2[i][j];
    }
    for (int i = 0;i < 8;i  )
    {
        for (int j = 0;j < 8;j  )
        {
            std::cout << array1[i][j];
            std::cout << "  " << array2[i][j];
            std::cout << "  " << std::endl;
            std::cout << "both previous numbers added together = " << addition[i][j] << std::endl;
        }
    }
  //} - and you don't need this here
    return 0;
}

Take this example and compare to your code to see your mistake. Code just wasn't structured properly.

CodePudding user response：

Your code's logics are absolutely right! However, the mistake was found in improper bracket structuring on for loop. I have corrected your code and mentioned the mistakes as comments.

#include <iomanip>
#include <cstdlib>
#include <iostream> //include this header to use "cout"

using namespace std;

int main() {
    srand(time(0));
    
    int array1[8][8];
    int array2[8][8];
    int addition[8][8];
    
    for (int i = 0; i < 7; i  ) {
        for (int j = 0; j < 7; j  )
        array1[i][j] = rand() % 6;
    }
    for (int i = 0;i < 7; i  ) {
        for (int j = 0; j < 7; j  ) {
            array2[i][j] = rand() % 8;
        }
    }
    {
        for (int i = 0; i < 7; i  ) {
            for (int j = 0; j < 7; j  ) {
                addition[i][j] = array1[i][j]   array2[i][j];
            }
        }      //add this bracket
            for (int i = 0; i < 7; i  ) {
                for (int j = 0; j < 7; j  ) {
                    cout << array1[i][j];
                    cout << "  " << array2[i][j];
                    cout << "  " << endl;
                    cout << "both previous numbers added together = " << addition[i][j] << endl;
                //}   remove this bracket
            }
            return 0;
        }
    }
}

Also, to add on, if you want an 8x8 matrix use i<8 and j<8 everywhere in the code. Here you have used i<7 and j<7 which means you get a 7x7 matrix as result.

Logic: i=0 to i<7 use have => 0,1,2,3,4,5,6 (stopping at 6 because 6<7 is true and 7<7 becomes false naturally). So from 0 to 6 there are totally 7 elements.

Hope this helps! :)