Question

I have an matrix in this format that I am trying to validate and remove first row:

3 4 
0 0 0 
0 0 0
0 0 0
0 0 0

Where the first line is and the other lines are the actual data.

Width Height

What is the best way to A remove the first row, and B validate that all rows meet the Width Height Criteria specified? I could do a simple for loop and copy them but I am looking for a more elegant way to do it? Maybe with Linq or one of the Collection Methods?

So far I have:

 //add the split for correctness 
 string[][] lines = File.ReadAllLines(fileName).Select(x=>x.Split(' ')).ToArray();
 //first line is width/hight
 int length  = lines.Length ==0 ;
 if(|| (length > 0 && lines[0].Length !=2 ) ){
     throw new InvalidDataException("File is not correctly formated:" + fileName);
 }

 int width = lines[0][0];
 int hieght = lines[0][1];

 //Check Row count       
 if(length != height -1){
   throw new InvalidDataException("Invalid missing rows in the Matrix definition");
 }

 //make sure the file is correctly formated with width and height:    
 if(lines.Any(x=>x.Length != Width)){
     //I know this fails because of first line
     throw new InvalidDataException("Invalid Width in a row in the Matrix");
 }

Any suggestions on a better way to validate input?

Answer 1

sscanf would have been nice but I have done it with reg. exp. and it will check whether width and height is integers and it also checks every following number for being a integer:

static bool isValid(string path)
{
    var data = File.ReadAllText(path);

    var first = Regex.Match(data, @"\A *(\d+) +(\d+) *([\r\n|\n]|\Z)");

    if (!first.Success) return false;

    int width = int.Parse(first.Groups[1].Value);
    int height = int.Parse(first.Groups[2].Value);

    return Regex.Match(data, @"\A *\d+ +\d+ *((\r\n|\n)((^ *| +)\d+){" + width + @"} *){" + height + @"}\Z", RegexOptions.Multiline).Success;
}

I can make it more strict with regards to spaces.

Added A:

If you want to save all the lines, except the first, to a new path then this will do:

var lines = File.ReadLines(path);
File.WriteLines(path2, lines.Skip(1));

Or if you just want a array of the lines except the first, use this:

var linesExceptFirst = File.ReadLines(path).Skip(1);