python入门之（语法介绍）

>>> #python语句
>>> 
>>> ''' 1、程序由模块构成
2、模块包含语句
3、语句包含表达式
4、表达式建立并处理对象
'''
' 1、程序由模块构成\n2、模块包含语句\n3、语句包含表达式\n4、表达式建立并处理对象\n'
>>> 
>>> while True:
reply = input('Enter text:')
if reply == 'stop':
break
print(reply.upper())



Enter text:meto
METO
Enter text:youto
YOUTO
Enter text:stop
>>> 
>>> 
>>> while True:
reply = input('Enter text: ')
if reply == 'stop':
break
elif not reply.isdigit():
print('Bad' * 8)
else:
print(int(reply)**2)



Enter text: 3
9
Enter text: 5
25
Enter text: sd
BadBadBadBadBadBadBadBad
Enter text: 56
3136
Enter text: stop
>>> 
>>> 
>>> #try语句处理错误
>>> while True:
reply = input('Enter text: ')
if reply == 'stop':
break
try:
num = int(reply)
except:

SyntaxError: invalid syntax
>>> while True:
reply = input('Enter text: ')
if reply == 'stop':
break
try:
num = int(reply)
except:
print('Bad' * 8)
else:
print(int(reply) ** 2)
print('Bye!')



Enter text: 7
49
Bye!
Enter text: 87
7569
Bye!
Enter text: df
BadBadBadBadBadBadBadBad
Bye!
Enter text: stop