How to determine height and length of a 2D array from stdin? - c

Question

My program has to read contents of a file like so:
name_of_program < Test.txt
Test.txt is a 2D array of integers (integers are separated by spaces, sometimes multiple ones, rows of integers are separated by EOL), but of unknown length and height. How do I determine them?
I plan on storing each row in a node of a linked list as an array of integers.
EDIT: My program roughly looks like this:
#include <stdio.h>
#include <stdlib.h>
struct node {
int *val; //stores the row
struct node *next;
};
struct node *addnode(int *val, struct node *next);
struct node *mergesort(struct node *head, int column); //column by which I'll sort it
struct node *merge(struct node *head_one, struct node *head_two, int column);
int main(int column) //number of column to sort by, should run like that "name_of_program column < Test.txt" in Unix systems
{
struct node *head;
struct node *current;
struct node *next;
head = NULL;
/* Reading from stdin line by line, writing it to list and linking nodes - I have only the last bit done */
head = mergesort(head, column);
/* Writing to stdout, row by row of sorted list, I can't do that without the previous bit */
for(current = head; current != NULL; current = next)
next = current->next, free(current);
return 0;
};
struct node *addnode(int *val, struct node *next)
{
struct node *tnode;
tnode = (struct node*)malloc(sizeof(*tnode));
if(tnode != NULL) {
tnode->val = val; //not sure about this line, would it write whole array, or just one element?
tnode->next = next;
};
return tnode;
}
struct node *mergesort(struct node *head, int column)
{
struct node *head_one;
struct node *head_two;
if((head == NULL) || (head->next == NULL))
return head;
head_one = head;
head_two = head->next;
while((head_two != NULL) && (head_two->next != NULL)) {
head = head->next;
head_two = head->next->next;
};
head_two = head->next;
head->next = NULL;
return merge(mergesort(head_one, column), mergesort(head_two, column), column);
}
struct node *merge(struct node *head_one, struct node *head_two, int column)
{
struct node *head_combined;
if(head_one == NULL)
return head_two;
if(head_two == NULL)
return head_one;
if(head_one->val[column] < head_two->val[column]) {
head_combined = head_one;
head_combined->next = merge(head_one->next, head_two, column);
} else {
head_combined = head_two;
head_combined->next = merge(head_one, head_two->next, column);
};
return head_combined;
}

Answer 1

You can start by reading file line by line in C you can use getline function.
You will need to allocate sufficiently large buffer considering maximum length of line.
Process the line, retrieving integers from line, this can be done by looping through line buffer
and skipping white spaces. The integers can be stored either in 2D array or linked list which you can created.