40. while循环写法：

例如： while i<=10：print(i)   i+=1

方法一，用for：

he = 0
for i in range(1,101):
    he += i

print(he)

方法二，用while：

he = 0
i = 1
while i < 101:
    he += i
    i += 1
print(he)

i = 0
he = 0
while i<100:
    i = i + 1
    he = he + i
print(he)
print(i)

另一种写法