FILE HANDLING

Membuka file

Format umum

f = open("file.txt", "r")

Tetapi cara terbaik menggunakan context manager

with open("file.txt", "r") as f:
  data = f.read()

Karena:

• lebih aman dari error
• file otomatis ditutup
• lebih clean

Mode open file

Contoh

with open("file.bin", "rb") as f:
  content = f.read()

Read file

Baca seluruh isi file

with open("data.txt", "r") as f:
  content = f.read()

Baca per baris

with open("data.txt") as f:
  for line in f:
    print(line.strip())

Baca seluruh baris sebagai list

with open("data.txt") as f:
  lines = f.readlines()

Write File

Overwrite file

with open("output.txt", "w") as f:
  f.write("Hello world!")

Append

with open("output.txt", "a") as f:
  f.write("\nNew line appended.")

Read and Write file besar (streaming)

• Jika file sangat besar (1GB+), jangan pakai read()
• Gunakan streaming

  with open("big.log") as f:
    for line in f:
      process(line)
  

Lebih memory efficient karena:

• tidak load seluruh file
• baca baris per baris

JSON File Handling

Baca JSON

import json

with open("data.json") as f:
  data = json.load(f)

print(data)

Tulis JSON

with open("data.json", "w") as f:
  json.dump(data, f, indent=4)

CSV File Handling

Read CSV

import csv

with open("data.csv") as f:
  reader = csv.reader(f)
  for row in reader:
    print(row)

With header

with open("data.csv") as f:
  reader = csv.DictReader(f)
  for row in reader:
    print(row["name"], row["age"])

Write CSV

with open("out.csv", "w", newline="") as f:
  writer = csv.writer(f)
  writer.writerow(["name", "age"])
  writer.writerow(["Pythonia", 25])

Binary File (Images, Videos, PDF)

Read Binary

with open("photo.jpg", "rb") as f:
  content = f.read()

Write binary

with open("copy.jpg", "wb") as f:
  f.write(content)

Error handling pada File

try:
  with open("missing.txt") as f:
    data = f.read()
except FileNotFoundError:
  print("File tidak ditemukan.")

Exception umum

• FileNotFoundError
• PermissionError
• IsADirectoryError
• IOError

Best Practice File Handling

• Selalu gunakan with open(...)
• Pakai encoding utf-8:

  with open("file.txt", "r", encoding="utf-8"):
  

• Jangan pakai .read() untuk file besar
• Gunakan CSV/JSON module
• Gunakan pathlib untuk path modern

  from pathlib import Path
  
  p = Path("data.txt")
  print(p.read_text())
  

Pathlib (modern file handling)

Pathlib lebih pythonic daripada string path

from pathlib import Path

p = Path("folder/data.txt")
print(p.exists())
print(p.is_file())

Read file

text = Path("test.txt").read_text()

Write File

Path("test.txt").write_text("hello dunia")