Creating a matrix in a structure - c

Question

I am trying to create a structure that will have two integer values, an array, and two 2-D matrices using my code below. I can initialize the structure with the integers and array just fine, and my 'Gen' function will create the random values I want for the array.
However, when I try adding in the matrix components, I run into a problem. My compiler gives me a warning: "initialization from incompatible pointer type". If I understand what I have read so far, this is because the structure needs to be pointed to an array of pointers that represent each row in the matrix. I don't know the syntax for that.
A quick note: the other topics I've seen that are related to this issue all initialize the structure in a function other than the main() function, so I haven't found those solutions helpful.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <math.h>
#include <string.h>
// Define structure
typedef struct {
int row;
int col;
int *arr;
int **mat1;
int **mat2;
}container;
// Function headers
void Gen(container Thing);
int main() {
int row = 5;
int col = 6;
int A[row];
int M1[row][col];
int M2[row][col+1];
// Initialize structure
container Object = {row, col, A, M1, M2};
// Run "Gen" function
Gen(Object);
int i, j; // Index variables
// Display the array
for(i = 0; i < row; i++)
{
printf("%i ", Object.arr[i]);
}
printf("\n\n");
// Display the numbers from the matrices
for(j = 0; j < Object.row; j++)
{
for(i = 0; i < Object.col; i++)
{
printf("%i ", Object.mat1[j][i]);
}
printf("\n");
}
printf("\n");
for(j = 0; j < Object.row; j++)
{
for(i = 0; i < Object.col; i++)
{
printf("%i ", Object.mat2[j][i]);
}
printf("\n");
}
return (EXIT_SUCCESS);
}
// Function to generate random values in the array & matrices
void Gen(container Thing)
{
int i, j;
srand(time(NULL));
// Generate random values for the array
for(i = 0; i < Thing.row; i++)
{
Thing.arr[i] = rand() % 5;
}
// Generate random values for the matrix
for(j = 0; j < Thing.row; j++)
{
for(i = 0; i < Thing.col; i++)
{
Thing.mat1[j][i] = rand() % 5;
Thing.mat2[j][i] = rand() % 5;
}
}
} // End of "Gen" function

Answer 1

container Object = {row, col, A, M1, M2};
is wrong since the type of M1 is int[row][col], which can decay to int (*)[col] but not to int**. You have the same problem with M2.
You'll need to rethink your strategy for generating a container.
For example:
int main() {
int row = 5;
int col = 6;
int A[row];
int* M1[row];
int* M2[row];
for ( int i = 0; i < row; ++i )
{
M1[i] = malloc(sizeof(M1[i][0])*col);
M2[i] = malloc(sizeof(M1[i][0])*(col+1));
}
// Initialize structure
container Object = {row, col, A, M1, M2};
...
for ( int i = 0; i < row; ++i )
{
free(M1[i]);
free(M2[i]);
}
return (EXIT_SUCCESS);
}