⭐ Top Python Interview Questions on Strings & Variables (With Real Interview Examples)

 

Python interviews always include questions on variables and strings, because they are the foundation of every Python program. Whether you're preparing for a job interview, a coding round, or just brushing up your skills, this guide covers the most frequently asked and real industry questions.

Let’s dive in.

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🔹 What Are Variables in Python?

In Python, a variable acts as a container that stores data values.
Example:

name = "John"
age = 25

Variables do not need explicit declaration—they’re created when you assign a value.

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🔹 What Are Strings in Python?

A string is a sequence of characters enclosed in single (' ') or double (" ") quotes.

Example:

message = "Hello, Python!"

Strings are immutable, meaning once created, they cannot be changed in place.

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🚀 Top 10 Interview Questions on Strings & Variables

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1. What is a variable? How is memory allocated to it?

Variables store references to objects in memory.
Python uses dynamic typing, so memory depends on the object, not the variable.

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2. What are valid and invalid variable names?

Valid:

_name, age1, city_name, number123

Invalid:

1name, city-name, for, while

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3. What is the difference between local and global variables?

• Local variable: Defined inside a function

• Global variable: Defined outside any function

x = 10  # global

def func():
    y = 5  # local

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4. What is a string?

A string is an immutable sequence of Unicode characters.

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5. How do you access characters in a string?

s = "Python"
print(s[0])   # P
print(s[-1])  # n

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6. What is string slicing?

s = "Python"
print(s[1:4])  # yth

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7. Why are strings immutable?

Because Python stores strings in memory as fixed objects for performance and security.

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8. How do you join and split strings?

" ".join(["Python", "Rocks"])
"Python Rocks".split()

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9. How do you convert between string and integer?

int("10")
str(25)

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10. How do you find the length of a string?

len("hello")

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🔥 Real Interview Questions (Frequently Asked in TCS, Wipro, Infosys, Cognizant)

These questions are collected from real interviews of freshers and entry-level Python roles.

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11. What is the difference between == and is for strings?

• == → checks value equality

• is → checks object identity

a = "hello"
b = "hello"
print(a == b)  # True
print(a is b)  # Could be True (due to interning)

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12. How do you reverse a string in Python?

s = "hello"
print(s[::-1])  # olleh

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13. How do you check if a string is palindrome?

s = "madam"
print(s == s[::-1])  # True

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14. How do you remove whitespace from a string?

s = "   python   "
print(s.strip())

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15. How do you count occurrences of a character in a string?

"banana".count("a")

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16. What is string interpolation?

Three methods:

name = "John"
print(f"My name is {name}")  # f-string
print("My name is {}".format(name))
print("My name is %s" % name)

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17. How do you swap two variables in Python without a third variable?

a, b = b, a

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18. How do you check if a variable is a string?

isinstance(x, str)

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19. What is the difference between upper() and capitalize()?

"python".upper()      # PYTHON
"python programming".capitalize()  # Python programming

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20. How do you remove duplicates from a string?

s = "banana"
output = "".join(dict.fromkeys(s))
print(output)  # ban

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🎁 Bonus: Must-Know String Functions

s.lower()
s.upper()
s.title()
s.replace("old", "new")
s.startswith("a")
s.endswith("z")

These are often asked in coding rounds.

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