# 10.10. Exercises: Functions¶

To solve 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 solve problems with code, you need to be skilled at writing functions. And to master functions, you need to write a lot of them.

These exercises ask you to write many 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 called `makeSquare(size)` that returns a `size` by `size` string of hashes. The function should NOT print each row of the square. Instead, it must return a single string that contains the entire shape.

Tip

1. Call your `makeLine` function to create each row of the square.
2. The newline character, `\n`, will be helpful to you.
3. Do NOT include a newline character at the end of your string.
```console.log(makeSquare(5));
```

Console Output

```#####
#####
#####
#####
#####
```

Warning

For each of the shape exercises, do not include a newline character at the very end of your string. While the final `\n` might not be noticeable for the simpler shapes, including it 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

```#
##
###
####
#####
```
2. 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.

3. 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 `'#'`.