Difference between revisions of "ASCII Art Examples"
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2. The second line starts at position (0,9), then at (1,8), then at (2,7), and so on... Try adding the X and Y values together for each occurrence of a "*" on the grid. You'll notice that the value is always equal to 9. We've figured out the pattern for the second line through the grid!<br \><br \> | 2. The second line starts at position (0,9), then at (1,8), then at (2,7), and so on... Try adding the X and Y values together for each occurrence of a "*" on the grid. You'll notice that the value is always equal to 9. We've figured out the pattern for the second line through the grid!<br \><br \> | ||
| − | We now know that if any of the two conditions above hold while we iterate through our grid, then we'll draw a "*", otherwise we'll draw a " ". Now we just need to figure out how we'll iterate through our grid in code. | + | We now know that if any of the two conditions above hold while we iterate through our grid, then we'll draw a "*", otherwise we'll draw a " ". Now we just need to figure out how we'll iterate through our grid in code. We're going to use 2 nested for-loops to iterate through our grid. The outer for-loop will represent the current row, and the inner for-loop will represent the current column. The code will look something like this:<br \> |
| − | We're going to use 2 nested for-loops to iterate through our grid. The outer for-loop will represent the current row, and the inner for-loop will represent the current column. The code will look something like this:<br \> | + | |
<pre> | <pre> | ||
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}//end for | }//end for | ||
</pre> | </pre> | ||
| + | |||
| + | The way this works is:<br \> | ||
| + | - Start at row 0 and column 0<br \> | ||
| + | - Iterate through columns 0 to 9 (staying at row 0)<br \> | ||
| + | - Go to the next row (row 1)<br \> | ||
| + | - Iterate through columns 0 to 9 (staying at row 1)<br \> | ||
| + | - Repeat until we've iterated through all rows | ||
| + | |||
}} | }} | ||
Revision as of 13:57, 6 April 2010
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ProblemIn this sample problem, we'll examine how to create a number of different "pictures" using two nested loops and printing characters to the console. These pictures include: a solid box, a solid box with a blank "X", an "X", a hollow box, a hollow box with an "X", and a right triangle. The program will begin by prompting the user for a number. This number will represent the size for each picture that will be printed to the console. In essence, the size will represent the number of rows and columns for each picture. |
SideSectionTitle
An image or By Students section | |
|---|---|---|
SolutionBefore we can actually start to think about solving these problems, we'll need to a piece of paper and a pencil. Each picture can be represented by a 2-dimensional grid, so let's draw out a 10 x 10 grid on our piece of paper. It may look something like this: 0 1 2 3 4 5 6 7 8 9 +–––––––––––––––––––––––––––––+ 0|__|__|__|__|__|__|__|__|__|__| 1|__|__|__|__|__|__|__|__|__|__| 2|__|__|__|__|__|__|__|__|__|__| 3|__|__|__|__|__|__|__|__|__|__| 4|__|__|__|__|__|__|__|__|__|__| 5|__|__|__|__|__|__|__|__|__|__| 6|__|__|__|__|__|__|__|__|__|__| 7|__|__|__|__|__|__|__|__|__|__| 8|__|__|__|__|__|__|__|__|__|__| 9|__|__|__|__|__|__|__|__|__|__| The best way in attempting to solve these problems is to draw each picture in the grid that you've drawn out for yourself. Let's use the picture of an "X" as an example: 0 1 2 3 4 5 6 7 8 9 +–––––––––––––––––––––––––––––+ 0|* |__|__|__|__|__|__|__|__|* | 1|__|* |__|__|__|__|__|__|* |__| 2|__|__|* |__|__|__|__|* |__|__| 3|__|__|__|* |__|__|* |__|__|__| 4|__|__|__|__|* |* |__|__|__|__| 5|__|__|__|__|* |* |__|__|__|__| 6|__|__|__|* |__|__|* |__|__|__| 7|__|__|* |__|__|__|__|* |__|__| 8|__|* |__|__|__|__|__|__|* |__| 9|* |__|__|__|__|__|__|__|__|* | Now that we've drawn out the "X", let's try to figure out the pattern: 1. Start at position (0,0). Look at the X and Y values for this particular line through the grid. Each of the X and Y values are the same! This means that whenever position X is equal to position Y, then we'll draw a "*". We've figured out the pattern for one of the two lines on the grid, now we need to figure out the pattern for the second line. 2. The second line starts at position (0,9), then at (1,8), then at (2,7), and so on... Try adding the X and Y values together for each occurrence of a "*" on the grid. You'll notice that the value is always equal to 9. We've figured out the pattern for the second line through the grid! We now know that if any of the two conditions above hold while we iterate through our grid, then we'll draw a "*", otherwise we'll draw a " ". Now we just need to figure out how we'll iterate through our grid in code. We're going to use 2 nested for-loops to iterate through our grid. The outer for-loop will represent the current row, and the inner for-loop will represent the current column. The code will look something like this:
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
//code here
}//end for
System.out.println(); // print a "return-character" to go to the next row
}//end for
The way this works is: - Start at row 0 and column 0 | ||
CodeSolutionCode goes here. Please DO NOT put your code in <pre> tags! | ||
import javax.swing.*; // so we can use JOptionPane to get user input
public class ASCII_Art
{
public static void main(String[] args)
{
String input; // what we'll be using for input... we'll parse each input string to an int
int size; // we'll read this value in from the console
// this command allows the user to enter a number which will determine the size of our pictures
input = JOptionPane.showInputDialog("Enter a number for the size of each picture",null);
//now we need to parse our input string to an integer
size = Integer.parseInt(input);
//solid box
//we're just printing the same number of '*'s for each row
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
System.out.print("*");
}//end for
System.out.println();
}//end for
System.out.println();
//solid box w/ an 'X'
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
if (i == j || j ==(size-1)-i)
{
System.out.print(" ");
}//end if
else
{
System.out.print("*");
}//end else
}//end for
System.out.println();
}//end for
System.out.println();
// an 'X'
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
if (i == j || j ==(size-1)-i)
{
System.out.print("*");
}//end if
else
{
System.out.print(" ");
}//end else
}//end for
System.out.println();
}//end for
System.out.println();
// a hollow box
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
if ((i == 0 || i == (size-1)) || (j == 0 || j == (size-1)) )
{
System.out.print("*");
}//end if
else
{
System.out.print(" ");
}//end else
}//end for
System.out.println();
}//end for
System.out.println();
//Hollow box w/ an 'X'
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
if (i == j || j ==(size-1)-i)
{
System.out.print("*");
}//end if
else if ((i == 0 || i == (size-1)) || (j == 0 || j == (size-1)) )
{
System.out.print("*");
}//end else if
else
{
System.out.print(" ");
}//end else
}//end for
System.out.println();
}//end for
System.out.println();
//right triangle
for (int i = 0; i < size; i++)
{
for (int j = 0; j < size; j++)
{
if (j <= i)
{
System.out.print("*");
}//end if
else
{
System.out.print(" ");
}//end else
}//end for
System.out.println();
}//end for
System.out.println("*** END OF PROCESSING. ***");
}//end main
}//end ASCII_Art
