Rainfall collector

int[,] w = new int[x, y];

In this example, w is declared as a 2D array of integers with x rows and y columns.

Columns and rows don't really exist in the computer memory. They are just an abstraction that makes it easier for us to understand. Whether x is a row or y is a row doesn't matter. By convention, in this example x would be a row but how you visualise the table is up to you.

List<List<int>> w = new List<List<int>>();

In this example, w is declared as a 2D list of integers.

Reading CSV files

Data can be stored in comma separated file (CSV) format, where each row (record) has data separated into columns (fields) by commas.

If the number of rows and columns is known, you can use a 2D array initialised with two for loops as shown above. If the number of rows is not known, a 2D list will be needed with new rows added to the list as they are read from the file.

This is a common operation when using files and 2D lists. Here is some boilerplate code that can be used to read data from a file and return it in a 2D list called database.

static List<List<string>> ReadFile(string filename)

{

List<List<string>> database = new List<List<string>>();

StreamReader file = new StreamReader(filename);

string line;

while ((line = file.ReadLine()) != null)

{

string[] fields = line.Split(',');

for (int i = 0; i < fields.Length; i++)

{

fields[i] = fields[i].Trim();

}

List<string> fieldList = new List<string>(fields);

database.Add(fieldList);

}

file.Close();

return database;

}