#Artificial Intelligence-AI-PHYTON
o Variables
and Simple Data Types:-
·
What Really Happens When You Run
hello_world.py.
(a)
Let’s
take a closer look at what Python does when you run hello_world.py. As it turns
out, Python does a fair amount of work, even when it runs a simple program: print
("Hello Python world!") When you run this code, you should see this
output:
(i) Hello
Python world!
(b)
When
you run the file hello_world.py, the ending.py indicates that the file is a
Python program. Your editor then runs the file through the Python interpreter,
which reads through the program and determines what each word in the program
means. For example, when the interpreter sees the word print followed by
parentheses, it prints to the screen whatever is inside the parentheses. As you
write your programs, your editor highlights different parts of your program in
different ways. For example, it recognizes that print () is the name of a
function and displays that word in one color. It recognizes that "Hello Python world!" is not Python
code and displays that phrase in a different color. This feature is called
syntax highlighting and is quite useful as you start to write your own
programs.
o
Variables
(a)
Let’s
try using a variable in hello_world.py. Add a new line at the beginning of the
file, and modify the second line: message = "Hello Python world!"
print(message) Run this program to see what happens. You should see the same
output you saw previously:
(b)
Hello
Python world! We’ve added a variable named message.
(c)
Every
variable is connected to a value, which is the information associated with that
variable. In this case, the value is the "Hello Python world!" text.
Adding a variable makes a little more work for the Python Class interpreter.
(d)
When
it processes the first line, it associates the variable message with the
"Hello Python world!" text. When it reaches the second line, it
prints the value associated with the message to the screen. Let’s expand on this
program by modifying hello_world.py to print a second message.
o Add a blank line to hello_world.py, and then add two new lines of code: message = "Hello Python world!" print(message) message = "Hello Python Crash Course world!" print(message) Now when you run hello_world.py, you should see two lines of output: Hello Python world!
o
Naming and Using Variables
§
When
you’re using variables in Python, you need to adhere to a few rules and
guidelines. Breaking some of these rules will cause errors; another guide [1]lines
just help you write code that’s easier to read and understand. Be sure to keep
the following variable rules in mind:
§ Variable
names can contain only letters, numbers, and underscores. They can start with a
letter or an underscore, but not with a number. For instance, you can call a
variable message_1 but not 1_message. • Spaces are not allowed in variable
names, but underscores can be used to separate words in variable names. For
example, a greeting message works, but a greeting message will cause errors. •
Avoid using Python keywords and function names as variable names; that is, do
not use words that Python has reserved for a particular pro[1]grammatical purpose,
such as the word print. ITS
#pythonclass
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