n=n+1 放在print(s)的前/后的影响

# 1+2+3+4+5+6+.....+100 = ?

#关键在于,当n为时,才print(s)

n = 1
s = 0
while n < 101:
    s = s + n
    if n ==100:             #关键在于这一步, 我用if来判断,当n为100时,才print(s), 否则继续while循环
        print(s)
    n = n + 1