I am trying to solve the following problem -
Given a matrix of size M * N. Find the transpose of the matrix.
I intend to store the M*N matrix in an array of pointers and then use a function to return another array of pointers that contains the transpose of the original matrix. Here is the code I used (the code is in C language) -
#include<stdio.h>
#include<stdlib.h>
int **transpose(int **a, int m, int n);
int main()
{
int **array, m, n;
scanf("%d%d", &m, &n);
array=(int **)malloc(m*sizeof(int)); //allocating rows
for(int i=0; i<m; i++){
*(array+i)=(int *)malloc(n*sizeof(int)); //allocating columns
}
int i, j;
for(i=0; i<m; i++){
for(j=0; j<n; j++){
scanf("%d", *(array+i)+j); //reading input
}
}
int **tranp=transpose(array, m, n);
for(i=0; i<n; i++){
for(j=0; j<m; j++){
printf("%d ", *(*(tranp+i)+j)); //printing output
}
printf("\n");
}
return 0;
}
int **transpose(int **a, int m, int n)
{
int **b;
b=(int **)malloc(n*sizeof(int)); //allocating n rows for transpose
int i, j;
for(i=0; i<n; i++){
*(b+i)=(int *)malloc(m*sizeof(int)); //m columns for transpose
}
for(i=0; i<n; i++){
for(j=0; j<m; j++){
*(*(b+i)+j)=*(*(a+j)+i); //b[i][j] is assigned a[j][i]
}
}
return b; //the pointer to b[0][0] is returned
}
I first declared an array of pointers int **array and used the standard library malloc function to dynamically allocate M rows and N columns. Then I read the input and used the function transpose that has a return type int ** to generate the transpose of the array and assign it to the pointer tranp and print the transposed array.
However, this code works perfectly fine and prints the transposed array for M<5 and N<5. Whenever M>=5 or N>=5, I get the following message -
Process returned -1073741819 (0xC0000005)
I looked up about it and apparently (0xC0000005) is the error code returned because I am illegally accessing memory locations. I do not understand where have I gone wrong here. Why is it that this code works for all M and N less than 5 and fails otherwise?
