首先我们先写一个文本例子,将下列复制保存到txt即可;
3.14, 1
3.141, 2
3.1415, 3
3.1415926, 4
我们写了四行内容,其中每行包括两个元素,采用逗号分隔;实例中保存上述内容保存到pythonIODemo.txt文件;
with open('pythonIODemo.txt') as f:
contents = f.read()
print(contents)
其最后一行多出一行空行,是因为read()在读至末尾加上了一个空字符串,可以在打印内容上追加rstrip()方法消除;
3.1 将如下代码写入demo2.py文件中;
with open('pythonIODemo.txt') as f:
for line in f:
print(line)
3.2 执行python3 demo2.py
3.3 或将上述文件的每行存取进列表中,供后续操作:
with open('pythonIODemo.txt') as f:
lines = f.readLines()
for line in lines:
print(line.rstrip())
filenames = ['demo1.py','demo2.py','demo3.py']
for filename in filenames:
with open('pythonIODemo.txt') as f:
lines = f.readLines()
圆周率文件下载地址:https://github.com/ehmatthes/pcc/tree/master/chapter_10/
filename = 'pi_million_digits.txt'
with open(filename, 'r') as f:
lines = f.readlines()
piString = ''
for line in lines:
piString += line.rstrip()
birth = ''
while True:
birth = input('请输入生日: ')
if(birth == 'exit' || birth == 'quit'): # 输入exit或quit退出
break
if birth in piString:
print('您的生日在π中')
else:
print('您的生日不在π中')
将下列内容写入demo4.py
with open('pythonIODemo2.txt', 'w') as f:
for i in range(3):
f.write("I love Python!\n")
此时发现已经多出了一个文件pythonIODemo2.txt;
但是上面的操作有一个问题,就是会直接覆盖掉以前的内容,下面是在之前内容上附加内容(使用附加模式,第二个参数为‘a’):
我们继续执行demo4.py,发现并不会附加内容,而是直接覆盖;
新建demo5.py,将open()第二个实参‘w’改为‘a’
with open('pythonIODemo2.txt', 'a') as f:
for i in range(3):
f.write("I love Python!\n")
我们发现内容已经添加成功;
print(1/0)
try:
print(1/0)
except ZeroDivisionError:
print("0不能作为除数啊!")
else:
print("try块中没有发生异常,则打印此")
import json
data = [2,3,4,5,7]
filename = 'numbers.json'
with open(filename, 'w') as f:
json.dump(data, f)
import json
filename = 'numbers.json'
with open(filename, 'r') as f:
contents = json.load(f)
print(contents)