(1) 基本逻辑控制举例和编码风格规范
1.while死循环
2.for循环
3.if,elif,else分支判断
4.编码风格(官方建议)
版本:Python3.4
#function: endless loop
import time
i = 0
while 1:
i += 1
print(i)
time.sleep(3)
执行效果:
>>> import time
>>> i = 0
>>> while 1:
... i += 1
... print(i)
... time.sleep(3)
...
1
2
3
^CTraceback (most recent call last):
File "<stdin>", line 4, in <module>
KeyboardInterrupt
>>>
#function: usage "for"
for i in range(3):
print("old i = " + str(i))
i += 1
print("new i = " + str(i))
执行效果:
>>> for i in range(3):
... print("old i = " + str(i))
... i += 1
... print("new i = " + str(i))
...
old i = 0
new i = 1
old i = 1
new i = 2
old i = 2
new i = 3
>>>
#function: usage "if..elif..else.."
x = int(input("Please enter an integer: "))
if x < 0:
x = 0
print('Negative changed to zero')
elif x == 0:
print('Zero')
elif x == 1:
print('Single')
else:
print('More')
执行效果:
$ python3 if.py
Please enter an integer: -1
Negative changed to zero
$ python3 if.py
Please enter an integer: 0
Zero
$ python3 if.py
Please enter an integer: 1
Single
$ python3 if.py
Please enter an integer: 2
More