Format check with string methods

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which condition checks that a postcode is exactly 4 digits?

A code.isalpha() and len(code) == 4

B code.isdigit() and len(code) == 4

2. A student enters '6O12' (letter O instead of zero). What does '6O12'.isdigit() return?

A False

B True

3. Which code tests the pattern 'two letters then digits' for a code like 'WA123'?

A code[:2].isalpha() and code[2:].isdigit()

B code[:2].isdigit() and code[2:].isalpha()

4. Which statement about a format check is true?

A It proves the data is correct and really exists

B It tests that the text follows an expected pattern

5. A user enters the postcode '0000'. It passes code.isdigit() and len(code) == 4. What does this show?

A The format is valid, but the postcode may not be a real one

B The postcode must be correct because it passed the check

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1code.isdigit() and len(code) == 4		AA single = assigns a value instead of comparing. It should be len(code) == 4.
2plate[:2].isalpha() and plate[2:].isdigit()		BChecks that a postcode is made up of digits only and is exactly 4 characters long
3A format check can use slicing to test only part of a string, such as the first two characters being letters		Cif code.isdigit() and len(code) == 4:
4A correct pattern does not prove the data is correct, because 0000 passes the 4-digit postcode check but may not be a real postcode		Did_code[:2].isalpha()
5if code.isdigit and len(code) == 4:		EChecks that the first two characters are letters and the rest are digits
6if len(code) = 4 and code.isdigit():		Fisdigit is missing its brackets, so the method is not called. It should be code.isdigit().

Definitions

code.isdigit() and len(code) == 4

Fill in the Blanks

Complete each line of code by filling in the missing parts.

if code._______() and len(code) == 4:

if code.isdigit() and len(code) == _:

ok = ref[:2]._______() and ref[2:].isdigit()

if len(ref) == 6 ___ ref[:2].isalpha():

code = "0000" valid = code.isdigit() and len(code) == 4 print(_____) # True, but not a real code

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A code = "6000"

B ok = len(code) == 4

C ok = ok and code.isalpha()

D print(ok)

Question 2

A code = "6150"

B ok = code.isdigit()

C if len(code) = 4 and ok:

D print("Format OK")

Question 3

A plate = "AB123"

B letters = plate[:2]

C digits = plate[3:]

D print(letters.isalpha())

E print(digits.isdigit())

Question 4

A code = int(input("Code: "))

B if len(code) == 4:

C if code.isdigit():

D print("Format OK")

Question 5

A code = "AB123"

B a = code[:2].isalpha()

C b = code[2:].isdigit()

D if a or b:

E print("Pattern OK")

Answer Key

Format check with string methods

Section A: Quick Questions

B — code.isdigit() and len(code) == 4

A — False

A — code[:2].isalpha() and code[2:].isdigit()

B — It tests that the text follows an expected pattern

A — The format is valid, but the postcode may not be a real one

Section B: Match the Pairs

code.isdigit() and len(code) == 4 → Checks that a postcode is made up of digits only and is exactly 4 characters long

plate[:2].isalpha() and plate[2:].isdigit() → Checks that the first two characters are letters and the rest are digits

A format check can use slicing to test only part of a string, such as the first two characters being letters → id_code[:2].isalpha()

A correct pattern does not prove the data is correct, because 0000 passes the 4-digit postcode check but may not be a real postcode → if code.isdigit() and len(code) == 4:

if code.isdigit and len(code) == 4: → isdigit is missing its brackets, so the method is not called. It should be code.isdigit().

if len(code) = 4 and code.isdigit(): → A single = assigns a value instead of comparing. It should be len(code) == 4.

Section C: Definitions

code.isdigit() and len(code) == 4 — A format check tests that text follows an expected pattern, such as 4 digits for a postcode, using string methods like isdigit(), isalpha(), slicing and len().

Section D: Fill in the Blanks

if code.isdigit() and len(code) == 4:

ok = ref[:2].isalpha() and ref[2:].isdigit()

if len(ref) == 6 and ref[:2].isalpha():

code = "0000"
valid = code.isdigit() and len(code) == 4
print(valid)  # True, but not a real code

Section E: Spot the Error

C — A postcode must be 4 digits, so the check needs isdigit(). isalpha() tests for letters and would reject "6000". The line should be ok = ok and code.isdigit().

C — A single = is assignment and is a syntax error inside a condition. Comparing the length needs ==, so the line should be if len(code) == 4 and ok:.

C — The pattern is two letters then digits, so the digits start at index 2. plate[3:] skips the first digit and checks the wrong part. It should be digits = plate[2:].

A — A format check works on text. Converting to int means len(code) and code.isdigit() cause errors because integers have neither. The line should be code = input("Code: ").

D — The pattern is only correct when BOTH the letters part and the digits part pass. Using or lets a code with only one correct part through. It should be if a and b:.