Python小程序——进行奇偶求和

1、输出1~100的偶数

start = 1
while True:
    if start == 51:
        break
    print( start*2)
    start += 1

2、输出1~100的奇数

start = 1
while True:
    if start == 100:
        break
    if start%2 == 1:
       print(start)
    start += 1

3、输出1-2+3-4+.......+99-100的和

sum=0
start=1
while True:
    if start == 101:
        break
    if start%2 == 1:
        sum = sum+start
    if start%2 == 0:
        sum = sum - start
    start += 1
print(sum)