Question

python 编程问题

Write a function sum_from_to(start, end) that uses a while loop to compute the sum of the integers from start up to, but not including end. Don't forget to initialize!
Examples:
sum_from_to(3, 7) should evaluate to 18 (i.e. 3+4+5+6).
sum_from_to(3, 3) should evaluate to 0.

要求用while语句写一个方程

Answer 1

a=int(raw_input("请输入起始数字："))
print(a)
b=int(raw_input("请输入结束数字："))
print (b)

num=0
for i in range(a,b):
num=num+i
print ("计算结果为：")
print (num)

不好意思，我刚才用for写的，测试结果正确。你稍微改一下就能实现while循环。

Answer 2

直接：
>>> def sum_from_to(start, end):
return sum(range(start,end))

运行一下，结果为：
>>> sum_from_to(3,7)
18
>>> sum_from_to(3,3)
0

Answer 3

def sum_from_to(start, end):
if start > end:
print 'start must leter than end'
else:
i = 0
j = end - start
if j == 0:
return 0
else:
while i < j:
start = start + i
i += 1
return start

Answer 4

def sum_from_to(start, end):
sum = 0
while start < end:
sum += start
start += 1

return sum