# Bubble sort

The goal of this lab is to learn to apply reference parameters, and to
learn about `vectors`

.
Your task is to write and test the following procedures which work on
`double`

s and on `vector`

s of `double`

s:
As you write each procedure, extend your `main()`

so that
it tests the procedure.
- Write a procedure
`swap`

which swaps two
`double`

s. (Note that these are **not**
necessarily in vectors.)

- Write a procedure
`sortTwo`

which sorts two doubles, so
that the first argument becomes the smaller of the two arguments.

- Write a procedure
`displayVector`

that displays a
vector of `double`

s to `cout`

, putting a single
space between each vector element.

- Lastly, write a procedure
`sortVector`

which sorts a
vector of doubles. The algorithm will be discussed in class.

**Check-off:** When you have written and tested these procedures,
ask one of us to check you off.