Python(50)_for循环与while循环实现1-2+3...+99

#-*-coding:utf-8-*-

'''
计算 1-2+3-4+5...+99
'''
sum  = 0
for i in  range(1,100):
    if i%2 ==0:
        sum = sum - i
    else:
        sum +=i
print(sum)

---

#-*-coding:utf-8-*-

'''
计算 1-2+3-4+5...+99
'''
i = 1
sum  = 0
while i<100:
    if i%2 ==0:
        sum = sum - i
    else:
        sum +=i
    i= i+1
print(sum)