CODEWITHSUNDEEP
carrays
NameMyName
NameMyName

Reputation: 5

Arrays , replacing the first to another array with columnsto rows

I was learning arrays for like 3 to 4 days , and I get stuck on this task. What actually i need to do is replacing the values from first to second array but the column needs to be one half and that half to replace in rows. For example: We insert for n = 3; then the first array column is n*2 Like this 

1,2,3,4,5,6
7,8,9,10,11,12
13,14,15,16,17,18

And the exit need to be 

1,2,3
7,8,9
13,14,15
4,5,6
10,11,12
16,17,18

And the code that i write 

#include <stdio.h>
int main ()
{
    int n,m;
    scanf("%d",&n);
    int a=n*2,b=n;
    m=n*2;
    int firstarray[n][m],secondarray[a][b];
    int i,j,k,l;
    for(i=0;i<n;i++)
        for(j=0;j<m;j++)
        scanf("%d",&firstarray[n][m]);

        for(i=0;i<n;i++)
            for(j=0;j<m/2;j++)
            secondarray[i][j]=firstarray[i][j];

        for(i=0;i<n;i++){
            for(j=m/2;j<m;j++)
            {
                for(k=n;k<a;k++)
                    for(l=0;l<b;l++)
                    secondarray[k][l]=firstarray[i][j];
            }
        }

        for(i=0;i<a;i++)
        {
             for(j=0;j<b;j++){
                 printf("%d",secondarray[i][j]);
              }
             printf("\n");
         }  
}

Upvotes: 0

Views: 59

Answers (1)

ryyker
ryyker

Reputation: 23218

In this section, the scanf statement is attempting to access an array element that is out of bounds :

for(i=0;i<n;i++)
        for(j=0;j<m;j++)
        scanf("%d",&firstarray[n][m]);//use i,j indexes, not n,m initializers

I think this is probably just a typo, but using n & m this way exceeds the bounds of the array by 1 in each dimension.

Change to:

for(i=0;i<n;i++)
        for(j=0;j<m;j++)
        scanf("%d",&firstarray[i][j]);
                               ^  ^

Note that there are other problems downstream in your logic to do what you are showing. It is not a simple transpose where given your example input, the result would be:

1, 7, 13
2, 8, 14
3, 9, 15
4, 10, 16
5, 11, 17
6, 12, 18

Keeping in mind the shape of your original array is stored in memory as a contiguous series of int locations:

|1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|

So to do what you show the first loop series will need to assign values to the [6][3] array by a combination of picking the 1st three in memory, skip the next 3, and so on:

|1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|
 ^ ^ ^       ^ ^ ^          ^  ^  ^

Then to pick up the rest, start by skipping 3, assigning 3, skipping..., and so on.

|1|2|3|4|5|6|7|8|9|10|11|12|13|14|15|16|17|18|
       ^ ^ ^       ^  ^  ^           ^  ^  ^

This then requires playing with the indexing to get this transformation, so given your arrays are created as:

m=n*2;
int firstarray[n][m],secondarray[m][n];

And the inputs are given as shown in your post, populating secondarray is done in 2-stages:

    //get first 3 of 6 columns
    for(i=0;i<n;i++)
    {
        for(j=0;j<m/2;j++)
        {
            secondarray[i][j]=firstarray[i][j];
        }
    }


    //get second 3 of 6 columns
    for(i=0;i<n;i++)
    {
        for(j=3;j<m;j++)
        {
            secondarray[i+3][j-3]=firstarray[i][j];
        }
    }

Upvotes: 1

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