Python String Programs with Solutions

106 programs101 easy5 medium0 hard

106 string programs that cover slicing, searching, counting, replacing, splitting and joining text. They are among the most common Python interview questions, and each one has an explained solution with real output.

Before you start

Read the Strings & Methods and String Formatting & f-strings lesson first if the topic is new to you.

All programs

Build a string character by character

Python Practice › Loop Programs › Program 3

Build a string character by character

EasyLoop Programs · 3 of 90

Write a Python program that adds each character of a word from the user to an empty string.

Input

python

Output

Enter a word: python
python

Approach

Start with an empty string and append each character with +=.

Solution

Python

word = input("Enter a word: ")result = ""for ch in word:    result += chprint(result)

Outputtyped input: python

Enter a word: python
python

Line by line

Line 2

The empty string is the starting value.

Lines 3-4

Each loop pass appends one character.

Learn the concept

New to this topic? Read the lesson, then come back.

Loops: for & while lesson →

More loop programs

#4EasyCount even and odd numbers #5EasyPrint 0 to 6 except 3 and 6 #6EasyFibonacci series up to 20 #7EasyFizzBuzz from 1 to 30

← All 90 Loop Programs

Extract 10-digit mobile numbers

Python Practice › String Programs › Program 106

Extract 10-digit mobile numbers

EasyString Programs · 106 of 106

Write a Python program to get all 10-digit mobile numbers from a string.

Input

a paragraph containing short numbers and four 10-digit numbers

Output

['8988858683', '2312245566', '4532892234', '9999234355']

Approach

Match exactly 10 digits with word boundaries.

Solution

Python

import re text = """We have 2233 some employee8988858683whos 3455 mobile numbers are randomly distributed2312245566we want 453452 to get4532892234all the mobile numbers9999234355from this given string."""print(re.findall(r"\b\d{10}\b", text))

Output

['8988858683', '2312245566', '4532892234', '9999234355']

Line by line

Line 11

\b stops a match inside a longer number, and {10} requires exactly ten digits.

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#102EasyCollapse repeated characters #103EasyPrint a string 3 times #104EasyEach character on a new line #105EasyExtract email addresses

← All 106 String Programs

Extract email addresses

Python Practice › String Programs › Program 105

Extract email addresses

EasyString Programs · 105 of 106

Write a Python program to extract all email addresses from a string.

Input

a paragraph with four email addresses

Output

['john@gmail.com', 'jay@lic.com', 'hari@facebook.com', 'mery@hotmail.com']

Approach

A regex for “letters @ domain . extension”.

Solution

Python

import re text = """We have some employee whosjohn@gmail.comemail id's are randomly distributedjay@lic.comwe want to gethari@facebook.comall the emailmery@hotmail.comid's from this given string."""print(re.findall(r"[\w.+-]+@[\w-]+\.[\w.]+", text))

Output

['john@gmail.com', 'jay@lic.com', 'hari@facebook.com', 'mery@hotmail.com']

Line by line

Line 11

The pattern matches the name, “@”, a domain and at least one dot-separated extension.

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#106EasyExtract 10-digit mobile numbers

← All 106 String Programs

Each character on a new line

Python Practice › String Programs › Program 104

Each character on a new line

EasyString Programs · 104 of 106

Write a Python program to print each character on its own line.

Input

"python"

Output

p
y
t
h
o
n

Approach

Loop or print(*text, sep="\n").

Solution

Python

print(*"python", sep="\n")

Output

p
y
t
h
o
n

Line by line

Line 1

* unpacks the string into separate characters and sep="\n" puts each on its own line.

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#105EasyExtract email addresses #106EasyExtract 10-digit mobile numbers

← All 106 String Programs

Print a string 3 times

Python Practice › String Programs › Program 103

Print a string 3 times

EasyString Programs · 103 of 106

Write a Python program to print a string 3 times.

Input

"sqatools"

Output

sqatoolssqatoolssqatools

Approach

* 3.

Solution

Python

print("sqatools" * 3)

Output

sqatoolssqatoolssqatools

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#104EasyEach character on a new line #105EasyExtract email addresses #106EasyExtract 10-digit mobile numbers

← All 106 String Programs

Collapse repeated characters

Python Practice › String Programs › Program 102

Collapse repeated characters

EasyString Programs · 102 of 106

Write a Python program to replace each group of repeated characters with a single character.

Input

"aabbccdd"

Output

abcd

Approach

dict.fromkeys keeps one of each in order.

Solution

Python

print("".join(dict.fromkeys("aabbccdd")))

Output

abcd

Note

The result keeps the original order, “abcd”. The original sample’s “cabd” came from using a set, whose order is not defined.

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#103EasyPrint a string 3 times #104EasyEach character on a new line #105EasyExtract email addresses #106EasyExtract 10-digit mobile numbers

← All 106 String Programs

Swap case

Python Practice › String Programs › Program 101

Swap case

EasyString Programs · 101 of 106

Write a Python program to swap upper and lower case.

Input

"Learning Python"

Output

lEARNING pYTHON

Approach

swapcase().

Solution

Python

print("Learning Python".swapcase())

Output

lEARNING pYTHON

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#102EasyCollapse repeated characters #103EasyPrint a string 3 times #104EasyEach character on a new line #105EasyExtract email addresses

← All 106 String Programs

First repeated character and its index

Python Practice › String Programs › Program 100

First repeated character and its index

EasyString Programs · 100 of 106

Write a Python program to find the first character that repeats and the index of its first occurrence.

Input

"sqatools"

Output

('o', 4)

Approach

Remember the first index of each character; stop at the first repeat.

Solution

Python

text = "sqatools"first_seen = {}for i, ch in enumerate(text):    if ch in first_seen:        print((ch, first_seen[ch]))        break    first_seen[ch] = i

Output

('o', 4)

Line by line

Lines 4-6

The first character seen twice is reported with the index where it first appeared.

Note

The loop finds the repeat at the second “o”, so the answer is (“o”, 4): “o” repeats before “s” does.

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#101EasySwap case #102EasyCollapse repeated characters #103EasyPrint a string 3 times #104EasyEach character on a new line

← All 106 String Programs

Index of each character

Python Practice › String Programs › Program 99

Index of each character

EasyString Programs · 99 of 106

Write a Python program to print the index of each character in a string.

Input

"sqatools"

Output

Index of s is 0
Index of q is 1
Index of a is 2
Index of t is 3
Index of o is 4
Index of o is 5
Index of l is 6
Index of s is 7

Approach

enumerate() gives index and character.

Solution

Python

for i, ch in enumerate("sqatools"):    print(f"Index of {ch} is {i}")

Output

Index of s is 0
Index of q is 1
Index of a is 2
Index of t is 3
Index of o is 4
Index of o is 5
Index of l is 6
Index of s is 7

Learn the concept

New to this topic? Read the lesson, then come back.

Strings & Methods lesson → String Formatting & f-strings lesson →

More string programs

#100EasyFirst repeated character and its index #101EasySwap case #102EasyCollapse repeated characters #103EasyPrint a string 3 times

← All 106 String Programs