python3.6基础之分支和循环

一.分支语句
样例1：#输入一个月份的数字，返回对应月份名称的缩写
month=['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec']
m=int(input('请输入月份（数字表示）:'))
if m<1 or m>12:
print('输入不合法')
else:
print(month[m-1])

样例2：#摄氏温度和华氏温度的转换
val =input('请输入带温度符号的温度值（例如32c）')
if val[-1]in ['C','c']:
f=1.8*float(val[0:-1])+32
print('转换后的温度为：%.2fF'%f)
elif val[-1] in ['F','f']:
c=float(val[0:-1])-32
print('转换后的温度为：%.2fC'%c)
else:
print('输入有误')

二.for 循环for n in range(2,10):
for x in range(2,n):
if n%x==0:
print(n,'equals',x,'*',n//x)
break
else:
print(n,'is a prime number')
运行结果：
>>> 
2 is a prime number
3 is a prime number
4 equals 2 * 2
5 is a prime number
6 equals 2 * 3
7 is a prime number
8 equals 2 * 4
9 equals 3 * 3

>>> 
三.while循环#sum2.py
'''
连续输入多个数据（输入enter键结束）
输出这些数的平均数
'''
def main():
sum=0.0
count=0.0
xStr=input('Enter a number
(<enter> to quit)>>')
while xStr != '':
x=eval(xStr)
sum=sum+x
count=count+1
xStr=input('Enter a number (<enter to quit>)>>')
print('the average of the number is',sum/count)
main()
运行结果：
Enter a number(<enter> to quit)>>1
Enter a number (<enter to quit>)>>2
Enter a number (<enter to quit>)>>3
Enter a number (<enter to quit>)>>4
Enter a number (<enter to quit>)>>
the average of the number is 2.5

>>>