Shell Programming and Scripting

First of I would just like to state that I am not looking for you guys to just do my work for me, I do want to learn and actually understand everything that is happening.

Hey all, I am having trouble on this. What I need to do is... Write an executable C file that will take a text file (not a specific file, will be tested with many) that contains a NxN matrix and read it into a dynamically allocated array so that I can manipulate it however I would like.
I am fairly new to Unix and C and am having trouble with writing the code out.
I understand the steps needed by my program:
1. Use a loop to Scan or get (idk correct terminology) # of rows and columns in the test file.
2. Allocate the proper amount of memory (using malloc) based on the number of rows and columns.
3. Once memory is allocated, create 2d array of the needed size.
4. Loop through and store everything in the test file into the array.

I guess I am just not familiar enough with writing my own code in this language, and also doesn't help that I am doing this through a putty Debian server (not noob friendly IMO). Anything I write I usually end up just scrapping an hour after because I feel I have gotten nowhere with it and end up just overwhelmed by the problem at hand.

So would anyone mind helping me out in any way possible? I am willing to do whatever it takes to get a grasp on this stuff, I need to know this so if anyone would perhaps like to skype or something (I feel it would be much much easier that way) please let me know!

Welcome to forum!

You can use search tool as many posts are repeated here, if you can provide us sample input and expected output, its well and good

following post might be useful for you, which reads file and stores in 2d array

https://www.unix.com/302882682-post2.html

Is this a homework assignment? (Special rules apply to homework assignments in these forums.)

We don't do Skype here, everything is done in the forums so all of us can learn from the problems and answers archived here.

Please don't throw away your code! Show us what you have done so we can get an idea of what problems you're having.

The first thing I'd do if I were tackling a problem like this would be to ask a few questions:

1. No headers will be present, dimensions must be determined by reading the entire file.
2. No headings to label columns, the only text in the file will be the matrix itself.
3. They will be ints, range should be something like -100 to 100.
4. I'm not sure what you mean by this?
5. Single spaces will be the separator.
6. Something as simple as:

Code:

10 20 30 40
50 60 70 80
90 100 10 20

should work just fine.

Is this a homework assignment? If not, how will this software be used?

Now that we know that you're processing ints, "What is the format of the data in the files?" is asking if all of the values can be assumed to be decimal values with no "leading" zeroes? If there are leading zeros on input, should the value still be treated as decimal, or can it be treated as octal? Could there be hexadecimal values (with a leading 0x or 0X)?

Please show us your latest attempt at a solution!

Here is what I have right now.

Code:

#include <stdio.h>
#include <stdlib.h>

int main() {
  int n;
  int i=0;
  int j=0;
  scanf("%d", &n);
  int **array;
  array = malloc(n * sizeof(int *));

  if(array == NULL) {
    printf("Out of memory\n");
    exit(1);
  }

  for(i = 0; i < n; i++) {
    array[i] = malloc(n * sizeof(int));
    if(array[i] == NULL) {
      printf("Out of memory\n");
      exit(1);
    }

  }

  for(i = 0; i < n; i++) {
    for(j = 0; j < n; j++) {
      int k;
      scanf("%d", &k);
      array[i][j] = k;
      printf("%d ", array[i][j]);
    }
  }
}

When I run this on a test file (such as one shown above) it give me output:

Code:

20 30 40 50 60 70 80 90 100 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20.....repeating 20s

At this point, I am just trying to print out the matrix itself, so whatever is in the test file is what I would like to output, like so.

Code:

10 20 30 40
50 60 70 80
90 100 10 20

This tells me that either A. Something is wrong with how I am reading it into the array, or B. my print method is wrong.
Can anyone lead me in the right direction?

For the last time: Is this a homework assignment? If not, how will this software be used?