Problem Scanning Integers with Comma Between Them into a 2d Array - c

Question

I am trying to write a C program that accepts a 2d matrix in the form of axb:{{a,b,c},{d,e,f}...} where a determines the number of rows and b determines the number of columns, the subunits {} declaring rows and the elements of rows are declared as a,b,c... between {}. The problem is the program only accepts matrices without commas between the elements so only matrices in the format axb:{{a b c},{d e f}...}} work. I want the program to be able to accept an input with commas between the variables. Here is the code for reference:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main() {
int a,b;
scanf("%dx%d:{", &a, &b);
int matrix[a][b];
int r,c;
for (r = 0; r < a; r++) {
scanf("{%d", &matrix[r][0]);
for(c = 1; c < (b -1); c++) {
scanf("%d", &matrix[r][c]);
}
scanf("%d},", &matrix[r][c]);
}
printf("%dx%d:{", b, a);
for (c = 0; c < (b - 1); c++) {
printf("{");
for(r = 0; r < (a - 1); r++) {
printf("%d,",matrix[r][c]);
}
printf("%d",matrix[r][c]);
printf("},");
}
printf("{");
for(r = 0; r < 3; r++) {
printf("%d,",matrix[r][c]);
}
printf("%d",matrix[r][c]);
printf("}");
printf("}\n");
return 0;
}

Answer 1

What I would do is scan the whole input and work with that afterwards.
#include <stdio.h>
#include <stdlib.h>
int main()
{
// scan the input matrix
int a, b;
char input[256];
scanf("%dx%d:%256[^\n]", &a, &b, input);
int mat[a][b];
// populate matrix:
char* p = input;
int i = 0;
while (p != input + 256)
{
// scan until the character is not a separator
if (*p == '{' || *p == '}' || *p == ',')
{
++p;
}
else
{
int n;
sscanf(p, "%d", &n);
mat[0][i] = n;
++i;
// scan until we find a separator character
while (p != input + 256 && (*p != '{' && *p != '}' && *p != ','))
{
++p;
}
if (i >= a*b)
break;
}
}
printf("your matrix:\n");
for (i = 0; i < a*b; ++i)
{
if (i % b == 0)
printf("\n");
printf("%d ", mat[0][i]);
}
printf("\n");
return 0;
}
Example input and output:
Input:
3x2:{{a, b},{c, d},{e, f}}
Output:
a b
c d
e f
where a, b, c, d, e and f are numbers (well, integers).
However this might not be an elegant solution, but it does what you'd asked for.
At the least it can give you some ideas. Hope this can be of help.
Note:
When indexing the array I used a single index i. You can do this because arrays like these are stored in an 1D array anyway. However this is just my laziness. Feel free to correct it.
If this is not what you had in mind or I made some mistakes feel free to correct me. Might have misunderstood something.