1,文本文件
普通打开
f.open
f.close
def main(): f = None try: f = open('致橡树.txt', 'r', encoding='utf-8') print(f.read()) except FileNotFoundError: print('无法打开指定的文件!') except LookupError: print('指定了未知的编码!') except UnicodeDecodeError: print('读取文件时解码错误!') finally: if f: f.close()if __name__ == '__main__': main()with关键字
with open as f
def main(): try: with open('致橡树.txt', 'r', encoding='utf-8') as f: print(f.read()) except FileNotFoundError: print('无法打开指定的文件!') except LookupError: print('指定了未知的编码!') except UnicodeDecodeError: print('读取文件时解码错误!')if __name__ == '__main__': main()for-in循环逐行读取或者用readlines方法将文件按行读取到一个列表容器中import timedef main(): # 一次性读取整个文件内容 with open('致橡树.txt', 'r', encoding='utf-8') as f: print(f.read()) # 通过for-in循环逐行读取 with open('致橡树.txt', mode='r') as f: for line in f: print(line, end='') time.sleep(0.5) print() # 读取文件按行读取到列表中 with open('致橡树.txt') as f: lines = f.readlines() print(lines)if __name__ == '__main__': main()写入文本文件
from math import sqrtdef is_prime(n): """判断市素数""" assert n > 0 for factor in range(2,int(sqrt(n) + 1)): if n %factor == 0: return False return True if n != 1 else Falsedef main(): filenames = ('a.txt', 'b.txt', 'c.txt') fs_list = [] try: for filename in filenames: fs_list.append(open(filename,'w',encoding='utf-8')) for num in range(1,10000): if is_prime(num): if num < 100: fs_list[0].write(str(num)+"\n") elif num < 1000: fs_list[1].write(str(num)+"\n") else: fs_list[2].write(str(num)+'\n') except IOError as e: print(e) print("文件写入错误") finally: for fs in fs_list: fs.close() print("操作完成")if __name__ == '__main__': main()
2,二进制文件
def main(): try: with open('guido.jpg', 'rb') as fs1: data = fs1.read() print(type(data)) # with open('吉多.jpg', 'wb') as fs2: fs2.write(data) except FileNotFoundError as e: print('指定的文件无法打开.') except IOError as e: print('读写文件时出现错误.') print('程序执行结束.')if __name__ == '__main__': main() 3，json文件
JSON跟Python中的字典其实是一样一样的，事实上JSON的数据类型和Python的数据类型是很容易找到对应关系的，如下面两张表所示。
| JSON | Python |
|---|---|
| object | dict |
| array | list |
| string | str |
| number (int / real) | int / float |
| true / false | True / False |
| null | None |
| Python | JSON |
|---|---|
| dict | object |
| list, tuple | array |
| str | string |
| int, float, int- & float-derived Enums | number |
| True / False | true / false |
| None | null |
我们使用Python中的json模块就可以将字典或列表以JSON格式保存到文件中，代码如下所示。
import jsondef main(): mydict = { 'name': '骆昊', 'age': 38, 'qq': 957658, 'friends': ['王大锤', '白元芳'], 'cars': [ {'brand': 'BYD', 'max_speed': 180}, {'brand': 'Audi', 'max_speed': 280}, {'brand': 'Benz', 'max_speed': 320} ] } try: with open('data.json', 'w', encoding='utf-8') as fs: json.dump(mydict, fs) except IOError as e: print(e) print('保存数据完成!')if __name__ == '__main__': main()