Formatting structured data in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of JSON formatting with indent

What is the output of the following Python code that formats a dictionary as a JSON string with indentation?

Python

import json

data = {'name': 'Alice', 'age': 30, 'city': 'New York'}
result = json.dumps(data, indent=2)
print(result)

A

{
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

B {"name": "Alice", "age": 30, "city": "New York"}

C

{
"name": "Alice",
"age": 30,
"city": "New York"
}

D

{
  "name": "Alice",
  "age": 30,
  "city": "New York"
}

💡 Hint

Look at how json.dumps formats the output when indent=2 is used.

Using json.dumps with indent=2 formats the JSON string with two spaces before each key-value pair inside the braces, producing a nicely indented output.

❓ Predict Output

intermediate

Output of pretty-printing nested data

What is the output of this code that pretty-prints a nested dictionary using json.dumps with indent=4?

Python

import json

nested = {'user': {'name': 'Bob', 'details': {'age': 25, 'city': 'Paris'}}}
print(json.dumps(nested, indent=4))

A

{
    "user": {
        "name": "Bob",
        "details": {
            "age": 25,
            "city": "Paris"
        }
    }
}

B {"user": {"name": "Bob", "details": {"age": 25, "city": "Paris"}}}

C

{
  "user": {
    "name": "Bob",
    "details": {
      "age": 25,
      "city": "Paris"
    }
  }
}

D

{
"user": {
"name": "Bob",
"details": {
"age": 25,
"city": "Paris"
}
}
}

💡 Hint

Indent=4 means four spaces per level of nesting.

json.dumps with indent=4 adds four spaces for each nested level, so the output is deeply indented accordingly.

❓ Predict Output

advanced

Output of formatting a list of dictionaries with separators

What is the output of this code that formats a list of dictionaries as JSON with custom separators?

Python

import json

items = [{'id': 1, 'value': 10}, {'id': 2, 'value': 20}]
print(json.dumps(items, separators=(',', ':')))

A [{id:1,value:10},{id:2,value:20}]

B [{"id":1,"value":10},{"id":2,"value":20}]

C [{"id": 1, "value": 10},{"id": 2, "value": 20}]

D [{ "id": 1, "value": 10 }, { "id": 2, "value": 20 }]

💡 Hint

Separators=(',', ':') remove spaces after commas and colons.

The separators argument removes spaces after commas and colons, producing a compact JSON string without spaces.

❓ Predict Output

advanced

Output of sorting keys in JSON output

What is the output of this code that formats a dictionary as JSON with sorted keys?

Python

import json

data = {'b': 2, 'a': 1, 'c': 3}
print(json.dumps(data, sort_keys=True))

A {"c": 3, "b": 2, "a": 1}

B {"b": 2, "a": 1, "c": 3}

C {"a": 1, "b": 2, "c": 3}

D {"a":1,"b":2,"c":3}

💡 Hint

sort_keys=True orders keys alphabetically.

When sort_keys=True is used, keys are output in alphabetical order with spaces after colons by default.

🧠 Conceptual

expert

Effect of ensure_ascii=False in JSON formatting

Which option correctly describes the effect of using ensure_ascii=False in json.dumps when formatting data containing non-ASCII characters?

A The output JSON string contains the original non-ASCII characters instead of escaped Unicode sequences.

B The output JSON string escapes all characters, including ASCII, into Unicode sequences.

C The output JSON string raises a UnicodeEncodeError if non-ASCII characters are present.

D The output JSON string removes all non-ASCII characters from the data.

💡 Hint

Try printing json.dumps with and without ensure_ascii=False on data with accented letters.

By default, json.dumps escapes non-ASCII characters as Unicode sequences. Using ensure_ascii=False keeps the original characters in the output string.