Thread: Drawing a Box with Coordinates

Hello, I am a beginning student in a C programming class. I am having trouble understanding an assignment my instructor issued but has not lectured over it yet (it is due before she lectures over it).

The assignment is:

1) Write a program that asks the user for a a single character and two XY coordinates. The two X and two Y values should all be integers between 0 and 50. The character should be a printable ASCII character with values between and including ' !' (ascii value 33) and '~' (ascii value 126).

2) Your program should then draw a rectangle made up of the user selected character where the upper left corner is at X1; Y 1 and the lower right corner is at X2; Y2. Be sure to print the appropriate number of blank lines (having spaces in the blank rows is OK) in the beginning and pad each row of your rectangle with X1 leading spaces.

The Output is supposed to be similar to this:

(X1,Y1) = (0,0) , (X2,Y2) = (4,4), the character = ^

^^^^
^^^^
^^^^
^^^^

What I am having trouble understanding is printing between certain ASCII values (ASCII has never been discussed in class).

Another thing I am having trouble with is the main part of the assignment. From what we are currently discussing is loops and the assignment is covering nested loops. My code looks similar to this:

Code:

#include <stdio.h>

int main (void) {

int X1, Y1, X2, Y2;
char cRec;

printf("Enter a character: ");
scanf("%c", &cRec);
printf("\n");

printf("Enter point 1 (close to origin): ");
scanf("%d,%d", &X1, &Y1);
printf("\n");

printf("Enter point 2 (farthest from origin): ");
scanf("%d,%d", &X2, &Y2);
printf("\n");

for (X1=0; X1 <= X2; ++X1) {
     for (Y1=0; Y1 <= Y2; ++Y1) {
         printf("%c", cRec);
    }
}
return 0;
}

My thinking on the assignment is that you want the X1 coordinate to increase to the value of X2 (same for Y1 and Y2). Is this thinking wrong?

It's a bit more complicated than that, but not difficult.

You also want to use the values input for x1 and y1.

So the rectangle has not only a size specified by the input,
but also a specified location on the screen.

That's the purpose of this:

"Be sure to print the appropriate number of blank lines (having spaces in the blank rows is OK) in the beginning and pad each row of your rectangle with X1 leading spaces."

The blank lines and spaces position the recangle.

-

Originally Posted by ZeroBoyd

Isn't that what the printf and scanf functions were for? Or do I define two new terms, x1 and x2?

If (X1,Y1) is considered the upper left corner of the Rectangle, then you can consider Y1 the amount of '\n' characters you need to get to the correct y coordinate. The y axis usually starts at 0 at the top of the screen, and gets larger as you go down (think of how you read text). The X1 value is the number of ' ' characters to get to the correct x coordinate.

After printing each row, you will then need to print X1 number of ' ' characters before starting the new row. So I would recommend one loop before the rest, that prints Y1 number of '\n' characters, then a nested that prints X1 number of spaces before printing charaters.

Think of it like this:

X1 is x coordinate
Y1 is y coordinate (starting at top of screen)
X2 is X1 plus width
Y2 is Y1 plus height

Example:

X1 is 2,
Y1 is 2 (starting from --- line),
X2 is 6 (width of 4)
Y2 is 4 (height of 2)

----------------------------------------------


****
****

----------------------------------------------

(Please pretend the rectangle is 2 spaces from the left edge of my post, as it's not showing properly)



Page of ascii character values : Table of ASCII Characters

Thank you for your help. My current code is:

Code:

#include <stdio.h>
#include <math.h>

int main(void) {
   char cRec;
   int X1, Y1; //Point A
   int X2, Y2; //Point B
   int i;         //Height
   int j;         //Width

   printf("Enter a character: ");
   scanf("%c", &cRec);
   printf("\n");
 
   printf("Enter Point One (closest to origin): ");
   scanf("(%d,%d)", &X1, &Y1);
   printf("\n");
 
   printf("Enter Point Two (farthest from origin): ");
   scanf("(%d,%d)", &X2, &Y2);
   printf("\n");

   for (j = X1; j <= X2; j++) {
      printf("%c\n", letterRectangle);
      for (i = Y1; i <= Y2; i++) {
         printf("%c", letterRectangle);
      }
   }
   return 0;
}

From this, by entering in "*" for the character, "(0,0)" for Point 1 and "(4,4)" for Point 2 my box looks like:

*
******
******
******
******
*****

Could someone explain why this happens?

Looks like you posted the wrong code.
That code neither compiles nor works:

Code:

   printf("Enter Point One (closest to origin): ");
   scanf("(%d,%d)", &X1, &Y1);                     <<<<<  extra set of parentheses
   printf("\n");
 
   printf("Enter Point Two (farthest from origin): ");
   scanf("(%d,%d)", &X2, &Y2);                     <<<<<  extra set of parentheses
   printf("\n");

   for (j = X1; j <= X2; j++) {
      printf("%c\n", letterRectangle);                <<<<<  should be cRec
      for (i = Y1; i <= Y2; i++) {
         printf("%c", letterRectangle);               <<<<<  should be cRec

Also, basically, you want something like this:

Code:

    for(i = 0; i < Y1; i++)
    {
        code here to print blank lines before top of rectangle
    }
    
    for(i = Y1; i <= Y2; i++)
    {  
        for(j = 0; j < X1; j++)
        {
            code to print spaces before left of rectangle 
        }

        for(j = X1; j <= X2; j++)
        {
            code to print lines of rectangle (characters)
        }
    }

-

Originally Posted by ZeroBoyd

From this, by entering in "*" for the character, "(0,0)" for Point 1 and "(4,4)" for Point 2 my box looks like:

*
******
******
******
******
*****

Could someone explain why this happens?

Code:

   for (j = X1; j <= X2; j++) {
      printf("%c\n", letterRectangle);
      for (i = Y1; i <= Y2; i++) {
         printf("%c", letterRectangle);
      }
   }

First, you have x and y swapped. Because the rectangle is printed row by row,
and not column by column, you want y in the outer loop. (y represents rows).

Anyway, what's happening, is that you have an extra character being printed:

Code:

    printf("%c\n", letterRectangle);

You want only a newline in that printf statement.
Also, the newline should be just after the inner loop, not before.

Notice that a rectangle defined by (0, 0) and (4, 4) will be 5 by 5 characters.

Your output should look like this for (0, 0) and (4, 4):

Code:

*****
*****
*****
*****
*****

and like this for (10, 10) and (14, 14):

Code:

          *****
          *****
          *****
          *****
          *****

-

Thank you. So the main problem was the extra character in the new line statement. As well as not changing my char variable. This brings a different question. The code I generate now, using (0,0) and (4,4), generates a 5x5 box, but it is supposed to generate a 4x4 box.
The code I have now is:

Code:

for (j = Y1; j <= Y2; j++) {
  printf("\n");
  for (i = X1; i <= X2; i++) {
   printf("%c", letterRectangle);
  }
 }

And the code for a 4x4 Box is:

Code:

for (j = 1; j <= 4; j++) {
  printf("\n");
  for (i = 1; i <= 4; i++) {
   printf("%c", letterRectangle);
  }
 }

So, the code needs to represent the difference between the two points.
So when I define diffX = X2 -X1 and diffY = Y2 - Y1 as integers and use the following code:

Code:

for (j = 1; j <= diffY; j++) {
  printf("\n");
  for (i = 1; i <= diffX; i++) {
   printf("%c", letterRectangle);
  }
 }

The code continuously generates a massive wall (paragraph) going infinte with the character inputed. Help?

EDIT: Still looking into it, Values for X1 though Y2 are not being registered for DiffX and DiffY.

Glad you are making progress.

Program crashes can do unpredictable things.
I always restart the PC unless I know exactly why the program crashed.

As I mentioned above, it could be done like this:

Code:

    for(i = 0; i < Y1; i++)
    {
        code here to print blank lines before top of rectangle
    }
    
    for(i = Y1; i <= Y2; i++)
    {  
        for(j = 0; j < X1; j++)
        {
            code to print spaces before left of rectangle 
        }

        for(j = X1; j <= X2; j++)
        {
            code to print lines of rectangle
        }
    }

Normally, you would just print newlines in the very first loop above to print the blank lines:

Code:

    for(i = 0; i < Y1; i++)
    {
        printf("\n");
    }

But this part is interesting:

"Be sure to print the appropriate number of blank lines (having spaces in the blank rows is OK) in the beginning..."

In the method above, there would be no need to print spaces in the blank rows.

If you can use if statements (or if else statements), then there is another way
to do it, which would have spaces in the blank rows:

Code:

    for(i = 0; i <= Y2; i++)
    {  
        for(j = 0; j < X2; j++)
        {
            if i and j are within the rectangle, print the rectangle character
            if i and j are not within the rectangle, print a space
        }

        print a newline
    }

-

I may misunderstand the instructions but isn't this more of what is asked for?

Code:

~~~~~~~
!     !
!     !
!     !
~~~~~~~

That would be the rectangle with spaces inside. Then you would use the the new lines and leading spaces (or tabs) to position it on the screen in the corect position.

as I say, I may misunderstand the teachers instructions but that is what I got from it.

Going back and rereading the first post - I think I am wrong here. the rectangle is a filled rectangle after all.

Code:

$$$$$$$$$$
$$$$$$$$$$
$$$$$$$$$$
$$$$$$$$$$