Introductory Programming
Fall 2004

For next time:

1) Read Chapter 2 of How to Think...

2) follow the instructions in Chapter 2 of Olinux

But don't spend more than two hours, total.

    (pass/NR for sophomores by October 8)


Quick Linux review
------------------

User and superuser

Accounts and environments

The prompt  (typeahead)

Files and directories

The "working" directory

pwd, ls and cd

Commands, arguments and options


Maintenance
-----------

1) Can we boot?

2) Do we have a user account?

3) Have we updated?



The Python Interpreter
----------------------

Log is as a user and open a terminal.

Type "python"

$ python
Python 2.3.3 (#1, May  7 2004, 10:31:40)
[GCC 3.3.3 20040412 (Red Hat Linux 3.3.3-7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

The chevron >>> is the Python prompt.

Try this:

>>> 3+1
4

What you are running is the Python (interactive) interpreter.

If you type a statement, Python executes it.
If you type an expression, Python evaluates it and prints the result.

3+1 is a mathematical expression, and the result is 4

Try this:

>>> from math import *
>>> cos(pi)
-1.0

Again, Python evaluates the expression and prints the result.

Try this:

>>> print 'hello'
hello

This is a print statement; Python executes it, which has the
effect of displaying the word hello.

Now try this:

>>> print 'hello

I left off the close quotation mark.  What happens?

Congratulations!  You just made your first syntax error.

    (EOL = end of line character)


Exiting the interpreter
-----------------------

Press Control-c.

Type "quit"

Type "exit"

Press Control-d.



Topics from Chapter 1
---------------------

Compilers and interpreters.

Errors and debugging.


Preview of Chapter 2
--------------------

Evaluating expressions.

Executing statements.



Get started on Olinux Chapter 2.