Basic Syntax of Python
- Python is case sensitive. Hence a variable with name codingavengers is not same as CodingAvengers
- For path specification, python uses forward slashes. Hence if you are working with a file, the default path for the file in case of Windows OS will have backward slashes, which you will have to convert to forward slashes to make them work in your python script.For window's path
C:\folderA\folderB
relative python program path should beC:/folderA/folderB
- In python, there is no command terminator, which means no semicolon
;
or anything.So if you want to print something as output, all you have to do is:print "Hello, World!"
Oops! we just shared the first python program too with you. Yes, just one single statement. - In one line only a single executable statement should be written and the line change act as command terminator in python.To write two separate executable statements in a single line, you should use a semicolon
;
to separate the commands. For example,print "Hello, World!" ; print "This is second line"
- In python, you can use single quotes
''
, double quotes""
and even triple quotes''' """
to represent string literals.word = 'word' sentence = "This is a one line sentence." para = """This is a paragraph which has multiple lines"""
- In python, you can write comments in your program using a
#
at the start. A comment is ignored while the python script is executed.# this is a comment print "Hello, World!" # this is a # multiline comment
- Line Continuation: To write a code in multiline without confusing the python interpreter, is by using a backslash
\
at the end of each line to explicitly denote line continuation. For example,sum = 123 + \ 456 + \ 789
Expressions enclosed in( )
,[ ]
or{ }
brackets don't need a backward slash for line continuation. For example,vowels = ['a', 'e', 'i', 'o', 'u']
- Blank lines in between a program are ignored by python.
- Code Indentation: This is the most important rule of python programming. In programming language like Java, C or C++, generally curly brackets
{ }
are used to define a code block, but python doesn't use brackets, then how does python knows where a particular code block ends. Well python used indentation for this.It is recommended to use tab for indentation, although you can use spaces for indentation as well, just keep in mind that the amount of indentation for a single code block should be same.if True: print "Yes, I am in if block" # the above statement will not be # considered inside the if block
the correct way would be,if True: # this is inside if block print "Yes, I am in if block"
Also, the following code will give error, as the statements are differently indented:if True: # this is inside if block print "Yes, I am in if block" # this will give error print "me too"
again, the correct way to do so is to keep all the statements of a particular code block at same indentation.if True: # this is inside if block print "Yes, I am in if block" print "me too"
So these are some basic rules that you must know so that it becomes easier for us to learn various concepts of python programming in the coming tutorials.
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