QUOTATION AND COMMENTS IN PYTHON

Python allows single (‘), double (“) and triple (‘’’ or “””) quotes for string literals, provided that they match at the beginning and the end of the string. You can use triple quotes for strings that span multiple lines. The following examples are legal Python strings:

word = 'word'

line = "This is a sentence."

para = """This is a paragraph. This paragraph contains

more than one sentence."""

A string literal that begins with the letter “r” (for “raw”) treats everything as a literal character and “escapes” the meaning of meta characters, as shown here:

a1 = r'\n'

a2 = r'\r'

a3 = r'\t'

print('a1:',a1,'a2:',a2,'a3:',a3)

The output of the preceding code block is here:

a1: \n a2: \r a3: \t

You can embed a single quote in a pair of double quotes (and vice versa) in order to display a single quote or a double quote. Another way to accomplish the same result is to precede a single or double quote with a backslash (“\”) character. The following code block illustrates these techniques:

b1 = "'"

b2 = '"'

b3 = '\''

b4 = "\""

print('b1:',b1,'b2:',b2)

print('b3:',b3,'b4:',b4)

The output of the preceding code block is here:

b1: ' b2: "

b3: ' b4: "

A hash sign (#) that is not inside a string literal is the character that indicates the beginning of a comment. Moreover, all characters after the # and up to the physical line end are part of the comment (and ignored by the Python interpreter). Consider the following code block:

#!/usr/bin/python

# First comment

print("Hello, Python!")  # second comment

This will produce following result:

Hello, Python!

A comment may be on the same line after a statement or expression:

name = "Tom Jones" # This is also comment

You can comment multiple lines as follows:

# This is comment one

# This is comment two

# This is comment three

A blank line in Python is a line containing only whitespace, a comment, or both.