Interview question

How do you read and write JSON and CSV files in Python? Python में JSON और CSV files कैसे read और write करें?

Answer

# JSON - using the built-in json module
import json

data = {'name': 'John', 'age': 30, 'active': True}

# Writing JSON to a file
with open('user.json', 'w') as f:
    json.dump(data, f, indent=2)  # indent makes it human-readable

# Reading JSON from a file
with open('user.json', 'r') as f:
    loaded = json.load(f)
    print(loaded['name'])  # John

# Converting between JSON string and Python object without a file
json_string = json.dumps(data)     # dict -> JSON string
parsed = json.loads(json_string)   # JSON string -> dict

# CSV - using the built-in csv module
import csv

# Writing CSV
with open('users.csv', 'w', newline='') as f:  # newline='' avoids extra blank rows
    writer = csv.writer(f)
    writer.writerow(['name', 'age'])       # header
    writer.writerow(['John', 30])
    writer.writerow(['Jane', 25])

# Reading CSV
with open('users.csv', 'r') as f:
    reader = csv.reader(f)
    header = next(reader)  # skip header row
    for row in reader:
        print(row)  # ['John', '30']

# DictReader/DictWriter - work with rows as dictionaries (uses header automatically)
with open('users.csv', 'r') as f:
    dict_reader = csv.DictReader(f)
    for row in dict_reader:
        print(row['name'], row['age'])  # John 30

# JSON - built-in json module
import json

data = {'name': 'John', 'age': 30, 'active': True}

# JSON file में लिखना
with open('user.json', 'w') as f:
    json.dump(data, f, indent=2)

# JSON file पढ़ना
with open('user.json', 'r') as f:
    loaded = json.load(f)
    print(loaded['name'])  # John

# बिना file के string convert करना
json_string = json.dumps(data)
parsed = json.loads(json_string)

# CSV - built-in csv module
import csv

with open('users.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    writer.writerow(['name', 'age'])
    writer.writerow(['John', 30])

with open('users.csv', 'r') as f:
    reader = csv.reader(f)
    header = next(reader)
    for row in reader:
        print(row)

# DictReader - dictionaries की तरह
with open('users.csv', 'r') as f:
    dict_reader = csv.DictReader(f)
    for row in dict_reader:
        print(row['name'], row['age'])

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