一、從文件中讀取數據

open()函數

參數

• file 文件路徑
• mode

# 一
f = open('pi.txt','r',encoding='utf-8')
contents = f.read()
print(contents)

#二
with open('pi.txt') as line:
    content = line.read()
    # print(content)
    # rstrip()方法剔除字符串末尾空白
    print(content.rstrip())

1、逐行讀取

with open('pi.txt') as f:
    for line in f:
        print(line.rstrip())

2、讀取文件以列表格式返回

lines = []
with open('pi.txt') as f:
   lines = f.readlines()·
print(lines)

二、寫入文件

with open('a.txt','w',encoding='utf-8') as f:
    f.write('i like')

三、追加到文件

如果文件存在則在原文件內容后寫入，如果不存在則創(chuàng)建寫入

with open('a.txt','a',encoding='utf-8') as f:
    f.write('hello word')

四、異常

1、處理ZeroDivisionError異常

try-except代碼塊

try:
    print(2/0)
except ZeroDivisionError:
    print('by zero')

2、else代碼塊

try-except-else

依賴于try代碼塊成功執(zhí)行的代碼都放在else代碼塊中

print('請輸入兩個數');
print('enter q to quit');
while True:
    firstNum = input('first num')
    if(firstNum=='q'):
        break
    secondNum = input('second num')
    if(secondNum =='q'):
        break
    try:
        result = int(firstNum)/int(secondNum)
    except ZeroDivisionError:
        print('can not')
    else:
        print(result)

五、數據存儲

json.dump()

• 參數
  • 存儲的數據
  • 存儲數據的文件對象

json.load()

• 參數
  • 文件

import json
# fileName = 'nums.json'
# 存儲json格式數據
# nums= [1,2,2,3,4,5,6]
# with open(fileName,'w',encoding='utf-8') as f:
#     json.dump(nums,f)

#讀取json格式數據
with open(fileName) as f:
    nums = json.load(f)
print(nums)