with open('notes.txt', 'r', encoding='utf-8') as file:
    content = file.read()
    print(content[:50])  # 打印前50個(gè)字符

# 傳統(tǒng)方式（易出錯(cuò)）
file = open('data.txt', 'w')
file.write('重要數(shù)據(jù)')
# 忘記close()導(dǎo)致數(shù)據(jù)未保存！

# 正確方式（自動(dòng)關(guān)閉）
with open('data.txt', 'w') as file:
    file.write('自動(dòng)保存的數(shù)據(jù)')
# 離開(kāi)with塊后文件自動(dòng)關(guān)閉

with open('config.json', 'r') as f:
    full_content = f.read()  # 返回整個(gè)字符串
    print(full_content)

error_count = 0
with open('server.log', 'r') as f:
    for line in f:  # 逐行讀取，內(nèi)存占用恒定
        if 'ERROR' in line:
            error_count += 1
print(f"發(fā)現(xiàn){error_count}個(gè)錯(cuò)誤")

error_count = 0
with open('server.log', 'r') as f:
    for line in f:  # 逐行讀取，內(nèi)存占用恒定
        if 'ERROR' in line:
            error_count += 1
print(f"發(fā)現(xiàn){error_count}個(gè)錯(cuò)誤")

with open('output.txt', 'w') as f:
    f.write('第一行內(nèi)容\n')  # 必須手動(dòng)添加換行符

data = ['蘋(píng)果\n', '香蕉\n', '橙子\n']
with open('fruits.txt', 'w') as f:
    f.writelines(data)  # 不會(huì)自動(dòng)添加換行符！

clean_data = [f"{item}\n" for item in ['蘋(píng)果', '香蕉']]

with open('demo.txt', 'r+') as f:
    # 定位到第5個(gè)字節(jié)
    f.seek(5)
    # 讀取后續(xù)10個(gè)字符
    print(f.read(10))
    # 回到文件頭插入內(nèi)容
    f.seek(0)
    f.write('新開(kāi)頭')

# 復(fù)制圖片
with open('original.jpg', 'rb') as src:
    data = src.read()
with open('copy.jpg', 'wb') as dst:
    dst.write(data)

import struct
with open('data.bin', 'rb') as f:
    # 讀取4字節(jié)整數(shù)+8字節(jié)浮點(diǎn)數(shù)
    int_data, float_data = struct.unpack('if', f.read(12))

def analyze_log(log_path):
    errors, warnings = 0, 0
    with open(log_path, 'r') as f:
        for line in f:
            if 'ERROR' in line:
                errors += 1
            elif 'WARNING' in line:
                warnings += 1
    return errors, warnings

# 使用示例
err, warn = analyze_log('app.log')
print(f"錯(cuò)誤:{err} 警告:{warn}")

import csv

def clean_csv(input_path, output_path):
    with open(input_path, 'r') as infile, \
         open(output_path, 'w', newline='') as outfile:
        
        reader = csv.DictReader(infile)
        fieldnames = reader.fieldnames
        writer = csv.DictWriter(outfile, fieldnames=fieldnames)
        writer.writeheader()

        for row in reader:
            # 填充缺失的age字段為0
            row['age'] = row.get('age', '0')
            writer.writerow(row)

# 使用示例
clean_csv('raw_data.csv', 'cleaned_data.csv')

def process_large_file(file_path, chunk_size=1024*1024):  # 默認(rèn)1MB
    with open(file_path, 'r') as f:
        while True:
            chunk = f.read(chunk_size)
            if not chunk:
                break
            # 處理每個(gè)數(shù)據(jù)塊
            analyze_chunk(chunk)

def analyze_chunk(chunk):
    # 示例：統(tǒng)計(jì)塊中的IP地址
    ips = [line.split()[0] for line in chunk.splitlines() 
           if line.startswith('192.168')]
    print(f"發(fā)現(xiàn){len(ips)}個(gè)內(nèi)網(wǎng)IP")

import os

def safe_write(file_path, content):
    try:
        # 確保目錄存在
        os.makedirs(os.path.dirname(file_path), exist_ok=True)
        with open(file_path, 'w') as f:
            f.write(content)
    except IOError as e:
        print(f"文件寫(xiě)入失敗: {e}")
    except Exception as e:
        print(f"未知錯(cuò)誤: {e}")

# 使用示例
safe_write('backup/2025.log', '系統(tǒng)備份數(shù)據(jù)')

from pathlib import Path

# 路徑拼接
config_path = Path('config') / 'settings.ini'

# 檢查文件是否存在
if config_path.exists():
    print(config_path.read_text(encoding='utf-8'))

import tempfile

# 創(chuàng)建臨時(shí)文件（自動(dòng)刪除）
with tempfile.NamedTemporaryFile(mode='w+', delete=True) as tmp:
    tmp.write('臨時(shí)數(shù)據(jù)')
    tmp.seek(0)
    print(tmp.read())  # 輸出: 臨時(shí)數(shù)據(jù)
# 離開(kāi)with塊后文件自動(dòng)刪除

import mmap

with open('huge_file.dat', 'r+b') as f:
    # 映射整個(gè)文件到內(nèi)存
    with mmap.mmap(f.fileno(), 0) as mm:
        # 像操作字符串一樣處理文件
        print(mm[:100].decode('utf-8'))  # 讀取前100字節(jié)