Question

Given a 2d matrix of size N x M (which must be read from a file provided to you), transpose it into a M x N matrix where N is the number of rows and M is the number of columns.

void transpose(int n, int m, const int A[n][m], int AT[m][n]);

Write a main() program to test and demonstrate your function. Show your function works for, at minimum, 3x6 and 10x6 matrices.

Answer 1

// C program to transpose a matrix

#include <stdio.h>

#include <stdlib.h>

// function to transpose a matrix A and store the result in AT

void transpose(int n, int m, const int A[n][m], int AT[m][n])

{

               for(int i=0;i<n;i++)

               {

                              for(int j=0;j<m;j++)

                                             AT[j][i] = A[i][j];

               }

}

// test the above function

int main() {

               int n = 3, m= 6;

               int A1[3][6], AT1[6][3];

               int num =1;

               for(int i=0;i<n;i++)

               {

                              for(int j=0;j<m;j++)

                              {

                                             A1[i][j] = num;

                                             num++;

                              }

               }

               printf("\nOriginal Matrix: \n");

               for(int i=0;i<n;i++)

               {

                              for(int j=0;j<m;j++)

                                             printf("%d ",A1[i][j]);

                              printf("\n");

               }

               transpose(n,m,A1,AT1);

               printf("\nTranspose Matrix: \n");

               for(int i=0;i<m;i++)

               {

                              for(int j=0;j<n;j++)

                                             printf("%d ",AT1[i][j]);

                              printf("\n");

               }

               n = 10, m= 6;

               int A2[n][m], AT2[m][n];

               num =1;

               for(int i=0;i<n;i++)

               {

                              for(int j=0;j<m;j++)

                              {

                                             A2[i][j] = num;

                                             num++;

                              }

               }

               printf("\n\nOriginal Matrix: \n");

               for(int i=0;i<n;i++)

               {

                              for(int j=0;j<m;j++)

                                             printf("%d ",A2[i][j]);

                              printf("\n");

               }

               transpose(n,m,A2,AT2);

               printf("\nTranspose Matrix: \n");

               for(int i=0;i<m;i++)

               {

                              for(int j=0;j<n;j++)

                                             printf("%d ",AT2[i][j]);

                              printf("\n");

               }

               return 0;

}

//end of program

Output:

Answer 2

#include<stdio.h>
void transpose(int n, int m, const int A[n][m], int AT[m][n])
{
   int i,j;
   for(i=0;i<m;i++)
   {
       for(j=0;j<n;j++)
       {
           AT[i][j]=A[j][i];
       }
   }
   for(i=0;i<m;i++)
   {
       for(j=0;j<n;j++)
       {
           printf("%d ",AT[i][j]);
       }
       printf(" \n");
   }
}
int main()
{
   FILE *fp;
    int i,j,n=10,m=6;
   int A[n][m],AT[m][n];
    fp = fopen("transpose.txt", "r");

    if (fp == NULL)
    {
        printf("Can't open file for reading.\n");
    }
    else
    {
       for(i=0;i<n;i++)
       {
           for(j=0;j<m;j++)
           {
               fscanf(fp, "%d", &A[i][j]);
           }
       }
        fclose(fp);
    }
    for(i=0;i<n;i++)
       {
           for(j=0;j<m;j++)
           {
               printf("%d ",A[i][j]);
           }
           printf(" \n");
       }
       printf("\n\n\nTranspose=\n\n");
   transpose(n, m, A, AT);
   printf("\n\nsecond testcase\n\n");
   n=3;
    for(i=0;i<n;i++)
    {
           for(j=0;j<m;j++)
           {
               fscanf(fp, "%d", &A[i][j]);
           }
   }
   for(i=0;i<n;i++)
       {
           for(j=0;j<m;j++)
           {
               printf("%d ",A[i][j]);
           }
           printf(" \n");
       }
       printf("\n\n\nTranspose=\n\n");
   transpose(n, m, A, AT);

}
  

SCREENSHOTS

}

Input File 2D array