02-07: Exercises — String Methods¶

Notes reference: 02-07: String Methods — Complete Reference

Q1: Case methods¶

Given s = "data science with python", print it in uppercase, title case, and with the first letter capitalised.

Solution

s = "data science with python"
print(s.upper())       # DATA SCIENCE WITH PYTHON
print(s.title())       # Data Science With Python
print(s.capitalize())  # Data science with python

Q2: Content checks¶

Check whether each string meets the condition described:

"2024"        → all digits?
"Dhaka123"    → all alphanumeric?
"   \t\n"     → all whitespace?
"myVariable"  → valid Python identifier?

Solution

print("2024".isdigit())           # True
print("Dhaka123".isalnum())       # True
print("   \t\n".isspace())        # True
print("myVariable".isidentifier())# True

Q3: Search and count¶

In the string s = "the river flows through the green valley", find: - the index of the first "the" - the index of the last "the" - how many times "the" appears

Solution

s = "the river flows through the green valley"
print(s.find("the"))    # 0
print(s.rfind("the"))   # 24
print(s.count("the"))   # 2

Q4: Replace¶

Given text = "I love Java. Java is great. Java pays well.", replace all "Java" with "Python". Then replace only the first occurrence.

Solution

text = "I love Java. Java is great. Java pays well."
print(text.replace("Java", "Python"))       # all replaced
print(text.replace("Java", "Python", 1))    # only first replaced

Q5: Split and join¶

Split "Dhaka,Chittagong,Sylhet,Rajshahi" by ",", print the list, then join it back with " | ".

Solution

raw   = "Dhaka,Chittagong,Sylhet,Rajshahi"
parts = raw.split(",")
print(parts)               # ['Dhaka', 'Chittagong', 'Sylhet', 'Rajshahi']
print(" | ".join(parts))   # Dhaka | Chittagong | Sylhet | Rajshahi

Q6: Strip and clean user input¶

A user entered " jahid@email.com " (with extra spaces). Strip the whitespace, convert to lowercase, and check that it ends with ".com".

Solution

raw = "   jahid@email.com   "
clean = raw.strip().lower()
print(clean)                     # jahid@email.com
print(clean.endswith(".com"))    # True

Q7: Alignment and padding¶

Print a small price list where item names are left-aligned in a field of 12 and prices are right-aligned in a field of 8 with 2 decimal places.

Solution

print(f"{'Item':<12} {'Price':>8}")
print("-" * 22)
print(f"{'Notebook':<12} {35.00:>8.2f}")
print(f"{'Pen':<12} {12.50:>8.2f}")
print(f"{'USB Cable':<12} {250.00:>8.2f}")

Q8: Partition an email¶

Given email = "jahid.hassan@university.edu", use partition("@") to extract the local part and the domain separately.

Solution

email = "jahid.hassan@university.edu"
local, sep, domain = email.partition("@")
print(local)    # jahid.hassan
print(domain)   # university.edu

Q9: Translate / remove vowels¶

Remove all vowels from the string "programming in python" using str.maketrans and translate.

Solution

s = "programming in python"
table = str.maketrans("", "", "aeiou")
print(s.translate(table))   # prgrmmng n pythn

Q10: Practical — normalize a CSV line¶

Given line = " Alice , 30 , Engineer ", split by ",", strip whitespace from each part, and print the clean list.

Solution

line  = "  Alice , 30 , Engineer  "
parts = [p.strip() for p in line.split(",")]
print(parts)   # ['Alice', '30', 'Engineer']

# Without comprehensions (Section 06 — manual approach):
raw = line.split(",")
parts = [raw[0].strip(), raw[1].strip(), raw[2].strip()]
print(parts)

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