Python for + if MCQs (25) — Answers at the End

Python for + if MCQs (25)

Covers filtering inside loops, break/continue, for–else, nested loops, enumerate, list comprehensions with if, and common pitfalls. Answers at the end

Python Training in Vizag (Softenant)

1) What is the output?

for i in range(5):
    if i % 2 == 0:
        print(i, end=" ")
A. 0 2 4
B. 1 3
C. 0 1 2 3 4
D. (no output)

2) Count vowels using for+if:

count = 0
for ch in "python":
    if ch in "aeiou":
        count += 1
print(count)
A. 1
B. 2
C. 0
D. 3

3) Choose the output.

for i in range(3):
    for j in range(3):
        if i == j:
            print(i, end="")
A. 000
B. 012
C. 222
D. (no output)

4) Filtering into a list.

nums = [1, 2, 3, 4]
out = []
for n in nums:
    if n % 2:
        out.append(n * 2)
print(out)
A. [2, 6]
B. [2, 4, 6, 8]
C. [1, 3]
D. [4, 8]

5) Mind the break.

for i in range(3):
    if i == 1:
        break
    else:
        print(i, end=" ")
A. 0
B. 0 1
C. 1 2
D. (no output)

6) for–else + continue?

for i in range(3):
    if i == 1:
        continue
    print(i, end=" ")
else:
    print("|Done")
A. 0 2 |Done
B. 0 1 2 |Done
C. 0 2
D. |Done

7) Adjacent equal pairs.

s = "abba"
pairs = 0
for i in range(len(s)-1):
    if s[i] == s[i+1]:
        pairs += 1
print(pairs)
A. 0
B. 1
C. 2
D. 3

8) Iterating dictionary by key with a test.

d = {"a":1, "b":2}
for k in d:
    if d[k] % 2 == 0:
        print(k, end="")
A. a
B. b
C. ab
D. (no output)

9) for–else when a match occurs.

for i in range(1, 6):
    if i % 3 == 0:
        print("X")
        break
else:
    print("Y")
A. X
B. Y
C. XY
D. (no output)

10) for–else when no match occurs.

for i in range(1, 6):
    if i % 7 == 0:
        print("X")
        break
else:
    print("Y")
A. X
B. Y
C. (no output)
D. XY

11) Using enumerate with a test.

nums = [1, 2, 3]
for i, x in enumerate(nums):
    if i == x:
        print(i, end="")
A. 0
B. 1
C. 2
D. (no output)

12) Sum positives only.

out = 0
for n in [0, 0, 1, 0]:
    if not n:
        continue
    out += n
print(out)
A. 0
B. 1
C. 2
D. 3

13) Nested loops with skip.

for i in range(2):
    for j in range(3):
        if j == 1:
            continue
        print(f"{i}{j}", end=" ")
A. 00 01 02 10 11 12
B. 00 02 10 12
C. 01 02 11 12
D. 00 10

14) Bitwise test inside loop.

res = []
for x in range(5):
    if x & 1 and x > 1:
        res.append(x)
print(res)
A. [1, 3]
B. [3]
C. [2, 4]
D. []

15) List comprehension with if.

print([x*x for x in range(5) if x % 2 == 0])
A. [0, 4, 16]
B. [1, 9]
C. [0, 1, 4, 9, 16]
D. []

16) Conditional expression in a comp.

print([x if x % 2 == 0 else -x for x in range(3)])
A. [0, 1, 2]
B. [0, -1, 2]
C. [-0, -1, -2]
D. [1, 2, 3]

17) Count evens in triangular iteration.

total = 0
for i in range(3):
    for j in range(i):
        if j % 2 == 0:
            total += 1
print(total)
A. 1
B. 2
C. 3
D. 4

18) Using pass in branch.

for ch in "abc":
    if ch == "b":
        pass
    else:
        print(ch, end="")
A. abc
B. ac
C. b
D. (no output)

19) Dash for falsy, number otherwise.

nums = [0, 1, 2, 3]
for n in nums:
    if n:
        print(n, end="")
    else:
        print("-", end="")
A. -123
B. 0123
C. —
D. 123-

20) Compare pairs with a condition.

pairs = 0
for a in [1, 2]:
    for b in [2, 3]:
        if a < b:
            pairs += 1
print(pairs)
A. 2
B. 3
C. 4
D. 1

21) Early exit when odd found.

found = None
for n in [2, 4, 5, 6]:
    if n % 2 == 1:
        found = n
        break
else:
    found = 0
print(found)
A. 0
B. 5
C. 6
D. None

22) Collect lowercase characters only.

s = "PYthon"
lower = []
for ch in s:
    if ch.islower():
        lower.append(ch)
print("".join(lower))
A. python
B. thon
C. PY
D. (no output)

23) Non-empty lists with truthy first element.

data = [[], [1], [], [2, 3]]
count = 0
for lst in data:
    if lst and lst[0]:
        count += 1
print(count)
A. 1
B. 2
C. 3
D. 4

24) Break on zero.

acc = 1
for n in [0, 2, 3]:
    if not n:
        break
    acc *= n
print(acc)
A. 0
B. 1
C. 2
D. 6

25) Nested loop with guarded inner append.

result = []
for i in range(3):
    if i % 2 == 0:
        for j in range(2):
            if j == 1:
                break
            result.append((i, j))
print(result)
A. [(0, 0), (1, 0), (2, 0)]
B. [(0, 0), (2, 0)]
C. [(0, 1), (2, 1)]
D. []

Answer Key

1) A

2) A

3) B

4) A

5) A

6) A

7) B

8) B

9) A

10) B

11) D

12) B

13) B

14) B

15) A

16) B

17) B

18) B

19) A

20) B

21) B

22) B

23) B

24) B

25) B