Python Syntax


Execute Python Syntax

Python syntax, as we learned on the previous page, can be carried out by typing directly in the Command Line.

>>> print("Hello, World!")
Hello, World!

Alternatively, you can create a python file on the server with the .py file extension and run it from the command line :

C:\Users\Your Name>python myfile.py
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Python Indentation

The spaces at the beginning of a code line are referred to as indentation.

Where as indentation in code is only for readability in other programming languages, it is critical in Python.

In order to specify a code block, Python uses the indentation.

Example 1 :- With Indentation

if 5 > 2:
  print("Five is greater than two!")

Output :-

Five is greater than two!

Example 2:- Without indentation it gives syntax error :

if 5 > 2:
print("Five is greater than two!")

Output :-

File "demo_indentation_test.py", line 2
print("Five is greater than two!")
^
IndentationError: expected an indented block

Example 3 :- As a programmer, you decide number of spaces to use, but there must be at least one :

if 5 > 2:
 print("Five is greater than two!")  
if 5 > 2:
        print("Five is greater than two!") 

Output :-

Five is greater than two!
Five is greater than two!

In the same coding block, you have to use the same number of spaces, otherwise, Python will make the mistake :

Example 4:- Syntax Error with different number of spaces in a code block :

if 5 > 2:
 print("Five is greater than two!")
        print("Five is greater than two!")

Output :-

File "demo_indentation2_error.py", line 3
print("Five is greater than two!")
^
IndentationError: unexpected indent

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Python Variables

When a value is assigned to Python, variables are created :

Example :- Variables in Python :

x = 5
y = "Hello, World!"

print(x)
print(y)

Output :-

5
Hello, World!

Python has no command for expressing a variable.

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Comments

For the purpose of in-code documentation, Python has the capacity to comment.

Python will output the rest of the line as a comment if it begins with # :

Example :- Comments in Python :

#This is a comment.
print("Hello, World!")

Output :-

Hello, World!

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