Array of Arrays
An array of arrays, also called a jagged array because of its “unevenness” compared to a
standard n-dimensional array, is an array where each row is a one-dimensional array. Jagged
arrays can be declared and instantiated in a single statement—using side-by-side square
braces—but there is no way to initialize the elements of the jagged array in the same statement.
For example, here’s how you might declare a two-dimensional jagged string array, with the first
dimension having seven rows and the second dimension varying—considerably—in the number of elements:
const int rows = 7;
string [] [] jaggedA = new string [rows] [];
jaggedA[0] = new string [2];
jaggedA[1] = new string [3];
jaggedA[2] = new string [1];
jaggedA[3] = new string [4];
jaggedA[4] = new string [40];
jaggedA[5] = new string [2];
jaggedA[6] = new string [86];
Next, individual elements could be assigned values. For example:
jaggedA [1] [2] = "jagged";
Some of the jagged one-dimensional arrays within arrays are filled using iteration:
for (int dash = 0; dash < 86; dash++)
 jaggedA [6] [dash] = "-";
Next, each “column” can be displayed as a single concatenated item in a ListBox:
string column = "";
for (int i = 0; i < 2; i++) {
column = column + " " + jaggedA [0] [i] + " ";
}
lstMulti.Items.Add(column);
The listing below shows the rather messy code that does this for entire seven rows (messy because
with each “column” array a different size, nested iteration is not easily possible). If you run the
code, a graph depiction of “jaggedness” will appear in the ListBox.
Listing: Declaring, Populating and Displaying a Jagged String Array
private void btnJagged_Click(object sender, System.EventArgs e) {
// declare a jagged array with 7 rows
const int rows = 7;
string [] [] jaggedA = new string [rows] [];
// give it some column arrays
jaggedA[0] = new string [2];
jaggedA[1] = new string [3];
jaggedA[2] = new string [1];
jaggedA[3] = new string [4];
jaggedA[4] = new string [40];
jaggedA[5] = new string [2];
jaggedA[6] = new string [86];
// populate it
jaggedA [0] [0] = "This";
jaggedA [0] [1] = "is";
jaggedA [1] [0] = "a";
jaggedA [1] [1] = "very";
jaggedA [1] [2] = "jagged";
jaggedA [2] [0] = "array.";
jaggedA [3] [0] = "It";
jaggedA [3] [1] = "looks";
jaggedA [3] [2] = "extremely";
jaggedA [3] [3] = "uneven.";
// fill the final three columns with dashes (-)
for (int dash = 0; dash < 40; dash++)
jaggedA [4] [dash] = "-";
for (int dash = 0; dash < 2; dash++)
jaggedA [5] [dash] = "-";
for (int dash = 0; dash < 86; dash++)
jaggedA [6] [dash] = "-";
// display it
string column = "";
for (int i = 0; i < 2; i++){
column = column + " " + jaggedA [0] [i] + " ";
}
lstMulti.Items.Add(column);
column = "";
for (int i = 0; i < 3; i++){
column = column + " " + jaggedA [1] [i] + " ";
}
lstMulti.Items.Add(column);
column = "";
for (int i = 0; i < 1; i++){
column = column + " " + jaggedA [2] [i] + " ";
}
lstMulti.Items.Add(column);
column = "";
for (int i = 0; i < 4; i++){
column = column + " " + jaggedA [3] [i] + " ";
}
lstMulti.Items.Add(column);
column = "";
for (int i = 0; i < 40; i++){
column = column + jaggedA [4] [i];
}
lstMulti.Items.Add(column);
column = "";
for (int i = 0; i < 2; i++){
column = column + jaggedA [5] [i];
}
lstMulti.Items.Add(column);
column = "";
for (int i = 0; i < 86; i++){
column = column + jaggedA [6] [i];
}
lstMulti.Items.Add(column);
}
It’s time to move on! The next part of this crash course
explains why string manipulation is important and how string manipulation works in C#
|
