通常，一个程序都会有输入/输出，这样可以与用户进行交互。用户输入一些信息，你会对他输入的内容进行一些适当的操作，然后再输出给用户想要的结果。Python的输入/输出，我们可以用input进行输入，print进行输出，这些都是简单的控制台输入/输出，复杂的有处理文件等。
1. input和print
name = input("Please input your name:\n")
print("Hello,", name)
运行结果：
Please input your name:
known
Hello, known
2. 处理文件
poem = '''\
Programming is fun
When the work is done
if you wanna make your work also fun:
use Python!
'''
f = open('poem.txt', 'w') #open for 'w'riting
f.write(poem) #write text to file
f.close() #close the file
f = open('poem.txt')
#if no mode is specified, 'r'ead mode is assumed by default
while True:
line = f.readline()
if len(line) == 0:#Zero length indicates EOF
break
print(line),
#Notice comma to avoid automatic newline added by Python
f.close()#close the file
运行结果：
Programming is fun
When the work is done
if you wanna make your work also fun:
use Python!
open一个文件模式可以为读模式（'r'）、写模式（'w'）或追加模式（'a'），还有其他模式，你可以用help(open)来查看。