Python: 输入与输出 (I/O)

# 控制小数位数示例
x = 1/81
print(x)                # 0.012345679012345678
print('value: %.2f' % x)  # value: 0.01
print('value: %.5f' % x)  # value: 0.01235

# format() 方法示例
ss = 'My {pet} has {prob}'.format(pet='dog', prob='fleas')
print(ss)  # My dog has fleas

# 按位置替换
sss = 'My {0} has {1}'.format('dog', 'fleas')
print(sss)  # My dog has fleas

# 格式化浮点数
print('1/18 = {x:.3f}'.format(x=1/18))  # 1/18 = 0.056

# 写入文件
with open('story.txt', 'w') as f:
    f.write('Many had a little lamb,\n and then she had some more.\n')

# 读取文件
with open('story.txt', 'r') as f:
    content = f.read()

# 追加内容
with open('story.txt', 'a') as f:
    f.write('New line\n')

# 检查是否为 GIF 文件
def is_gif(fname):
    with open(fname, 'br') as f:
        first4 = tuple(f.read(4))
        return first4 == (0x47, 0x49, 0x46, 0x38)

import pickle

def save_data():
    grades = {
        'alan': [4, 8, 10, 10],
        'tom': [7, 7, 7, 8]
    }
    with open('grades.data', 'wb') as f:
        pickle.dump(grades, f)

def load_data():
    with open('grades.data', 'rb') as f:
        return pickle.load(f)

import urllib.request

def get_webpage(url):
    page = urllib.request.urlopen(url)
    return page.read()

import webbrowser

def open_webpage(url):
    return webbrowser.open(url)