10.10. Exercises: Functions

To become good at solving problems with code you need to be able to break large problems into small ones. Usually, these smaller problems will take the form of functions that are used to solve the larger problem. Therefore, to become good at solving problems you need to become good at writing functions. And to master functions, you need to write a lot of them.

These exercises ask you to write lots of relatively small functions, which combine to form larger, more complicated ones.

At the end, you will be able to create strings of shapes, like this nifty diamond:

    #
   ###
  #####
 #######
#########
#########
 #######
  #####
   ###
    #

There is no starter code for these exercises, so create a new Node.js project at repl.it to get started.

10.10.1. Rectangles

  1. Write a function makeLine(size) that returns a line with exactly size hashes.

    console.log(makeLine(5));
    

    Console Output

    #####
    
  2. Write a function makeSquare(size) that returns an size by size square of hashes. Use your makeLine function to do this.

    console.log(makeSquare(5));
    

    Console Output

    #####
    #####
    #####
    #####
    #####
    

    Tip

    The newline character, \n, will be helpful to you.

    Warning

    For this and all other functions in these exercises, make sure you do NOT have a newline character at the end of your string. Not only will console.log add a newline there for you, but having an extra newline at the end will make life harder for you toward the end of the exercises.

  3. Write a function makeRectangle(width, height) that returns a rectangle with the given width and height. Use your makeLine function to do this.

    console.log(makeRectangle(5, 3));
    

    Console Output

    #####
    #####
    #####
    
  4. Now, go back and rewrite makeSquare to use makeRectangle.

10.10.2. Triangles

  1. Write a function makeDownwardStairs(height) that prints the staircase pattern shown below, with the given height. Use your makeLine function to do this.

    console.log(makeDownwardStairs(5));
    

    Console Output

    #
    ##
    ###
    ####
    #####
    
  1. Write a function makeSpaceLine(numSpaces, numChars) that returns a line with exactly the specified number of spaces, followed by the specified number of hashes, followed again by numSpaces more spaces.

    console.log(makeSpaceLine(3, 5));
    

    Console Output

    ___#####___
    

    Note

    We have inserted underscores to represent spaces, so they are visible in the output. Don't do this in your code.

  2. Write a function makeIsoscelesTriangle(height) that returns a triangle of the given height.

    console.log(makeIsoscelesTriangle(5));
    

    Console Output

        #
       ###
      #####
     #######
    #########
    

    Tip

    Consider the top line of the triangle to be level 0, the next to be line 1, and so on. Then line i is a space-line with height - i - 1 spaces and 2 * i + 1 hashes.

10.10.3. Diamonds

  1. Write a function makeDiamond(height) that returns a diamond where the triangle formed by the top portion has the given height.

    console.log(makeDiamond(5));
    

    Console Output

        #
       ###
      #####
     #######
    #########
    #########
     #######
      #####
       ###
        #
    

    Tip

    Consider what happens if you create a triangle and reverse it using our reverse function.

10.10.4. Bonus Mission

Refactor your functions so that they take a single character as a parameter, and draw the shapes with that character instead of always using '#'. Make the new parameter optional, with default value '#'.