Python Tutorial | Python Strings



String Membership Test

We can test if a sub string exists within a string or not, using the keyword in and not in.

In operator

Example:

n="computer"
print("o" in n)
print("t" in n)
print("e" in n)
print("w" in n)
print("v" in n)
print("z" in n)

Output:

True
True
True
False
False
False
>>>

Example:

n="Hello World"
z="o" in n
print("z = ",z)
z="w" in n
print("z = ",z)
z="d" in n
print("z = ",z)

Output:

z = True
z = False
z = True
>>>

not In operator

Example:

n="computer"
print("o" not in n)
print("t" not in n)
print("e" not in n)
print("w" not in n)
print("v" not in n)
print("z" not in n)

Output:

False
False
False
True
True
True
>>>



Python String Formatting

Escape Sequence

If we want to print a text like:

He said, “What’s there?”

we can neither use single quote or double quotes. This will result into SyntaxError as the text itself contains both single and double quotes.

>>> print(“He said, “What’s there?””)

SyntaxError: invalid syntax
>>> print(‘He said, “What’s there?”‘)

SyntaxError: invalid syntax

One way to get around this problem is to use triple quotes. Alternatively, we can use escape sequences.

An escape sequence starts with a backslash and is interpreted differently. If we use single quote to represent a string, all the single quotes inside the string must be escaped.

Similar is the case with double-quotes. Here is how it can be done to represent the above text.

#single quote is allowed inside double quote

print(“single quote are allowed inside double quote”)
n=”hello how are you”
print(n)
n=”hello ‘how’ are you”
print(n)
n=”hello ‘how’ are ‘you'”
print(n)

output:

single-quote are allowed inside double quote
hello how are you
hello ‘how’ are you
hello ‘how’ are ‘you’

#double quote is allowed inside single quotes

print(“double quote are allowed inside single quote”)
n=’hello how are you’
print(n)
n=’hello “how” are you’
print(n)
n=’hello “how” are “you”‘
print(n)

output

double-quote are allowed inside single quote
hello how are you
hello “how” are you
hello “how” are “you”

To use a single quote within single quote

Example:
n=’hello how are you’
print(n)

#want output as : hello ‘how’ are you

n=’hello \’how\’ are you’
print(n)

#want output as : hello ‘how’ are ‘you’

n=’hello \’how\’ are \’you\”
print(n)

output
hello how are you
hello ‘how’ are you
hello ‘how’ are ‘you’

To use double quote within double quote

example:

n=”hello how are you”
print(n)

#want out put as : hello “how” are you
n=”hello \”how\” are you”
print(n)

#want out put as : hello “how” are “you”
n=”hello \”how\” are \”you\””
print(n)

hello how are you
hello “how” are you
hello “how” are “you”

# using triple quotes

print(”’He said, “What’s there?””’)

# escaping single quotes

print(‘He said, “What\’s there?”‘)

# escaping double quotes

print(“He said, \”What’s there?\””)

output:
He said, “What’s there?”
He said, “What’s there?”
He said, “What’s there?”



The format() Method for Formatting Strings

The format() method that is available with the string object is very versatile and powerful in formatting strings. Format strings contain curly braces {} as placeholders or replacement fields which get replaced.
We can use positional arguments or keyword arguments to specify the order.

# default(implicit) order
n=”{}, {} and {}”.format(‘Amit’,’Sumit’,’Harsh’)
print(n)

Amit, Sumit and Harsh

# order using positional argument
n="{0}, {1} and {2}".format('Amit','Sumit','Harsh')
print(n)

Output:

Amit, Sumit and Harsh
>>>

# order using positional argument
n=”{0}, {1} and {2}”.format(‘Amit’,’Sumit’,’Harsh’)
print(n)

Amit, Sumit and Harsh

# order using positional argument
n="{0}, {1} and {2}".format('Amit','Sumit','Harsh')
print(n)

Output:

Amit, Sumit and Harsh

# order using positional argument

n=”{1}, {0} and {2}”.format(‘Amit’,’Sumit’,’Harsh’)
print(n)

Sumit, Amit and Harsh

# order using positional argument
n="{1}, {0} and {2}".format('Amit','Sumit','Harsh')
print(n)

Output:

Sumit, Amit and Harsh

# order using positional argument
n=”{2}, {0} and {1}”.format(‘Amit’,’Sumit’,’Harsh’)
print(n)

Harsh, Amit and Sumit

# order using positional argument
n="{2}, {0} and {1}".format('Amit','Sumit','Harsh')
print(n)

Output:

Harsh, Amit and Sumit

# order using keyword argument

n=”{a}, {s} and {h}”.format(a=’Amit’,s=’Sumit’,h=’Harsh’)
print(n)

Amit, Sumit and Harsh

# order using keyword argument
n="{a}, {s} and {h}".format(a='Amit',s='Sumit',h='Harsh')
print(n)

Output:

Amit, Sumit and Harsh

# order using keyword argument

n=”{h}, {s} and {a}”.format(a=’Amit’,s=’Sumit’,h=’Harsh’)
print(n)

Harsh, Sumit and Amit

# order using keyword argument
n="{h}, {s} and {a}".format(a='Amit',s='Sumit',h='Harsh')
print(n)

Output:

Harsh, Sumit and Amit

Python Basic Programming Tutorial

Python Introduction     Getting started in Python Programming      Python propgramming fundamentals     Python Operators    Python If Condition     Python for loop    Python range construct      Python While loop    break and continue statements     Different looping techniques     Python List     Python String     Python Functions    Python Inbuilt Functions     Python Recursion     Using Python Library     Python Tuples     Python Dictionary     Python Sets     Python Strings     Python Exception Handling     Python Data File Handling

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