Sorting 2d matrix cols and rows in C - c

Question

Given set two - dimensional integers. The array consists of 5 rows and 10 columns.
Each value in the system is a random number between 0 and 20.
Have to write a program that performs the sorting of the array values as follows:
First there arrange the values in each column so that they are sorted in ascending order (top to bottom), then - so there can sort the columns right "comes right" by comparing pairs of values in different columns in the same row (a "comparison lexicography"): comparing two values ​​in two columns in the first row, if they are the same compared to the values in the second row, and so on, and accordingly change the order of columns (see example in the third printing of the array, below).
To display the array before sorting and after each of the two phases of the emergency.
for example :
I stuck with the sorting of the each cols. I don't get the sorting i want. I would like to get your help please.
This is my code:
#include "stdio.h"
#include "conio.h"
#include "malloc.h"
#include "stdlib.h"
#define N 5
#define M 10
#define LOW 0
#define HIGH 20
void initRandomArray(int arr[N][M]);
void printArray(int arr[N][M]);
void SortInColumn(int arr[N][M],int m);
int main()
{
int arr[N][M];
int m;
m=M;
srand((unsigned)time(NULL)); //To clear the stack of Random Number
initRandomArray(arr);
printf("Before sorting:\n");
printArray(arr);
printf("Sorting elements in each column:\n");
SortInColumn(arr,M);
system("pause");
return 0;
}
void initRandomArray(int arr[N][M])
{
int i,j;
for (i=0 ; i<N ; i++)
for (j=0 ; j<M ; j++)
{
arr[i][j]=LOW+rand()%(HIGH-LOW+1);
}
}
void printArray(int arr[N][M])
{
int i,j;
for (i=0 ; i<N ; i++)
{
for (j=0 ; j<M ; j++)
printf("%d ", arr[i][j]);
printf("\n");
}
}
void SortInColumn(int arr[][M],int m)
{
int i,j;
int temp;
for( i=m-1 ; i>=0 ; i--)
{
for(j=0; j<N-1; j++)
if (arr[i][j]>arr[i][j+1]) // compare adjacent item
{
temp=arr[i][j];
arr[i][j]=arr[i][j+1];
arr[i][j+1]=temp;
}
}
for (i=0 ; i<N ; i++)
{
for (j=0 ; j<M ; j++)
printf("%d ", arr[i][j]);
printf("\n");
}
}

Answer 1

This is mine, and it runs and gives the correct answer.
Basically, you did two things wrong.
you need three loops instead of two. The outer loop loops around each columns. the second loop makes sure you compare each column N-1 times since for each run you get one item in the right place. The inner loop do the adjacent comparison.
you need to change the comparison between arr[i][k] and arr[i][k+1] to arr[i][k] to arr[i+1][k]. Because you want to compare them in the same column, you hold the value k (column) unchanged and change the rows i.
void SortInColumn(int arr[][M],int m)
{
int i,j,k;
int temp;
for( k=0 ; k<m ; ++k)
{
for(j=0; j<N-1; j++)
{
for(i=0; i < N-1 - j; i++)
{
if (arr[i][k]>arr[i+1][k]) // compare adjacent item
{
temp=arr[i][k];
arr[i][k]=arr[i+1][k];
arr[i+1][k]=temp;
}
}
}
}
}
BTW, this algorithm is very bad in performance in general. You may want to try something else.

Answer 2

Let's look at your SortInColum function. I've changed the formatting to get a better understanding of what's going on, and renamed some variables.
void SortInColumn(int arr[][M],int m)
{
int row,col;
int temp;
for( row=m-1 ; row>=0 ; row--) // foreach row
{
for(col=0; col<N-1; col++) { // foreach column
if (arr[row][col]>arr[row][col+1]) { // comparing adjacent entries
// in different cols? Why?
temp=arr[row][col];
arr[row][col]=arr[row][col+1];
arr[row][j+1]=temp;
}
}
printArray(arr);
}
This function (given some changes) will sorts a single column, you can then call this for each column. Hopefully this gives you a good starting point.