What is the expected output of the following code? data = {} data[1] = 1 data['1'] = 2 data[1.0] = 4 res = 0 for d in data: res += data[d] print(res)

The correct answer is C. 6. Option C (6) is correct because Python considers integer 1 and float 1.0 as equal keys in a dictionary - they have the same hash value and compare equal (1 == 1.0 is True), so data[1.0] = 4 overwrites data[1] = 1. The final dictionary holds only two entries: key 1 (value 4) and…

Question

What is the expected output of the following code?
data = {}
data[1] = 1
data['1'] = 2
data[1.0] = 4
res = 0
for d in data:
res += data[d]
print(res)

Options

A3
BThe code is erroneous.
C6
D7

How the community answered

(19 responses)

A
11% (2)
B
5% (1)
C
79% (15)
D
5% (1)

Explanation

Option C (6) is correct because Python considers integer 1 and float 1.0 as equal keys in a dictionary - they have the same hash value and compare equal (1 == 1.0 is True), so data[1.0] = 4 overwrites data[1] = 1. The final dictionary holds only two entries: key 1 (value 4) and key '1' (value 2), giving res = 4 + 2 = 6.

Why the distractors fail:

D (7) is the most tempting trap - it assumes all three assignments create separate keys (1 + 2 + 4), but 1 and 1.0 collapse into one.
A (3) might arise from thinking 1.0 overwrites both integer entries and only '1' and one numeric key remain as 1 + 2, but that's not how it works either.
B (erroneous) is wrong because Python handles mixed numeric key types gracefully - no error is raised.

Memory tip: Remember "same hash, same key" - Python's dict uses hash equality, and integers/floats with the same numeric value always share a hash, so 1, 1.0, and even True are all the same dictionary key.

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