🌱 1. Print Name and Age

**Problem:**
Store your name and age in variables and print them together in a single line.

**Example Output:**

```
My name is Alice and I am 25 years old.

```

**Solution:**

```
name = "Alice"
age = 25
print(f"My name is {name} and I am {age} years old.")

```

**Explanation:**
Variables `name` and `age` store string and integer values.
`f-strings` help combine them cleanly without converting numbers to strings manually.

***

## 🔁 2. Swap Two Variables

**Problem:**
Swap values of `a` and `b`.

**Example:**

```
Input: a = 10, b = 20
Output: a = 20, b = 10

```

**Solution:**

```
a = 10
b = 20
a, b = b, a
print(a, b)

```

**Explanation:**
Python allows **tuple unpacking** — a quick and elegant way to swap variable values without a temporary variable.

***

## 🧩 3. String Concatenation

**Problem:**
Join two strings with a space between them.

**Example:**

```
Input: "Data", "Science"
Output: "Data Science"

```

**Solution:**

```
first = "Data"
last = "Science"
result = first + " " + last
print(result)

```

**Explanation:**
You can combine multiple strings using the `+` operator. Always remember to add spaces manually when needed.

***

## 🔢 4. Find String Length

**Problem:**
Find the length of a given string.

**Example:**

```
Input: "Python"
Output: 6

```

**Solution:**

```
s = "Python"
print(len(s))

```

**Explanation:**
`len()` returns the total number of characters in a string, including spaces and punctuation.

***

## ✂️ 5. Extract Substring

**Problem:**
From `"datascience"`, extract `"data"`.

**Solution:**

```
word = "datascience"
print(word[0:4])

```

**Explanation:**
Slicing uses the syntax `string[start:end]`.
Here, indices 0–3 (`data`) are taken, and the end index (4) is excluded.

***

## 🔠 6. Convert to Uppercase

**Problem:**
Convert a string to uppercase.

**Example:**

```
Input: "hello world"
Output: "HELLO WORLD"

```

**Solution:**

```
text = "hello world"
print(text.upper())

```

**Explanation:**
The `.upper()` method converts every alphabetic character to uppercase.

***

## 🔎 7. Count Occurrences of a Character

**Problem:**
Count how many times `'a'` appears in a string.

**Example:**

```
Input: "banana"
Output: 3

```

**Solution:**

```
word = "banana"
print(word.count("a"))

```

**Explanation:**
The `.count()` method counts all non-overlapping occurrences of a substring.

***

## 🔁 8. Replace a Word

**Problem:**
Replace `"apple"` with `"orange"` in a sentence.

**Example:**

```
Input: "I like apple"
Output: "I like orange"

```

**Solution:**

```
text = "I like apple"
new_text = text.replace("apple", "orange")
print(new_text)

```

**Explanation:**
`.replace(old, new)` substitutes every instance of `old` with `new`.

***

## 🔍 9. Check Substring Presence

**Problem:**
Check if the word `"code"` exists in the string `"I love to code in Python"`.

**Solution:**

```
sentence = "I love to code in Python"
print("code" in sentence)

```

**Explanation:**
The `in` operator returns `True` if a substring is present in a string, otherwise `False`.

***

## 🔄 10. Reverse a String

**Problem:**
Reverse the string `"python"`.

**Solution:**

```
s = "python"
print(s[::-1])

```

**Explanation:**
Using slicing with a step of `-1` (`[::-1]`) returns a reversed copy of the string.

***

## ⚙️ 11. Remove Whitespace

**Problem:**
Remove leading and trailing spaces.

**Example:**

```
Input: "   Hello World   "
Output: "Hello World"

```

**Solution:**

```
text = "   Hello World   "
print(text.strip())

```

**Explanation:**
`.strip()` removes spaces (or other whitespace) from both ends of a string.

***

## 💬 12. Format String

**Problem:**
Use variables to print a formatted message.

**Example Output:**

```
Alice scored 95 marks.

```

**Solution:**

```
name = "Alice"
score = 95
print(f"{name} scored {score} marks.")

```

**Explanation:**
`f-strings` make it easy to embed variable values directly inside text.

***

## 😂 13. Repeat a String

**Problem:**
Print `"ha"` 5 times.

**Solution:**

```
print("ha" * 5)

```

**Output:**

```
hahahahaha

```

**Explanation:**
Multiplying a string by a number repeats it that many times.

***

## 🅰️ 14. First and Last Character

**Problem:**
Print the first and last character of `"Python"`.

**Solution:**

```
word = "Python"
print(word[0], word[-1])

```

**Output:**

```
P n

```

**Explanation:**
Index `0` refers to the first character, and `-1` to the last one.

***

## 🧠 15. Capitalize First Letter

**Problem:**
Convert `"hello world"` → `"Hello world"`.

**Solution:**

```
text = "hello world"
print(text.capitalize())

```

**Explanation:**
`.capitalize()` converts only the **first letter** to uppercase and the rest to lowercase.

***

Store your name and age in variables and print them together in a single line.

name = "Alice"
age = 25
print(f"My name is {name} and I am {age} years old.")


 help combine them cleanly without converting numbers to strings manually.

Input: a = 10, b = 20
Output: a = 20, b = 10


 — a quick and elegant way to swap variable values without a temporary variable.

Join two strings with a space between them.

Input: "Data", "Science"
Output: "Data Science"


first = "Data"
last = "Science"
result = first + " " + last
print(result)


You can combine multiple strings using the 

 operator. Always remember to add spaces manually when needed.

 returns the total number of characters in a string, including spaces and punctuation.

) are taken, and the end index (4) is excluded.

Input: "hello world"
Output: "HELLO WORLD"


text = "hello world"
print(text.upper())


 method converts every alphabetic character to uppercase.

 method counts all non-overlapping occurrences of a substring.

Input: "I like apple"
Output: "I like orange"


text = "I like apple"
new_text = text.replace("apple", "orange")
print(new_text)


sentence = "I love to code in Python"
print("code" in sentence)


 if a substring is present in a string, otherwise 

Input: "   Hello World   "
Output: "Hello World"


text = "   Hello World   "
print(text.strip())


 removes spaces (or other whitespace) from both ends of a string.

Use variables to print a formatted message.

name = "Alice"
score = 95
print(f"{name} scored {score} marks.")


 make it easy to embed variable values directly inside text.

Multiplying a string by a number repeats it that many times.