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1.4. Words and sentences
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• Second you need to “tell a story”. In writing a story, you combine words
and sentences to convey an idea to the reader. There is a skill and art in
constructing the story and skill in story writing is improved by doing some
writing and getting some feedback. In programming, our program is the
“story” and the problem you are tryingto solve is the “idea”.
Once you learn one programming language such as Python, you will find it much
easier to learn a second programming language such as JavaScript or C++. The
new programming language has very different vocabulary and grammar but once
you learn problem solving skills, they will be the same across all programming
languages.
You will learn the “vocabulary” and “sentences” of Python pretty quickly. It will
take longer for you to be able to write a coherent program to solve a brand new
problem. We teach programming much like we teach writing. We start reading
and explaining programs and then we write simple programs and then write in-
creasingly complex programs over time. At some point you “get your muse” and
see the patterns on your own and can see more naturally how to take a problem
and write a program that solves that problem. And once you get to that point,
programming becomes a very pleasant and creative process.
We start with the vocabulary and structure of Python programs. Be patient as the
simple examples remind you of when youstarted reading for the firsttime.
1.4 Words and sentences
Unlike human languages, the Python vocabulary is actually pretty small. We call
this “vocabulary” the “reserved words”. These are words that have very special
meaning to Python. When Python sees these words in a Python program, they
have one and only one meaning to Python. Later as you write programs you will
make your own words that have meaning to you called variables. You will have
great latitude in choosing your names for your variables, but you cannot use any
of Python’s reserved words as a name for a variable.
In a sense, when we train a dog, we would use special words like, “sit”, “stay”,
and“fetch”. Alsowhenyou talk to adog and don’tuse any of the reservedwords,
they just look at you with a quizzical look on their faces until you say a reserved
word. For example, if you say, “I wish more people would walk to improve their
overallhealth.”, whatmostdogs likelyhear is, “blahblah blah walkblahblahblah
blah.” That is because “walk” is a reserved word in dog language. Many might
suggestthat the language between humans and cats has no reserved words
1
.
The reserved words in the language where humans talk to Python incudes the
following:
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http://xkcd.com/231/
