6.python 分支与循环

分支和循环

1、if 判断

写法1：

score = int(input('input score: '))

if 90 <= score <= 100:
    print('A')
if 80 <= score < 90:
    print('B')
if 60 <= score < 80:
    print('C')
if 0 <= score < 60:
    print('D')
if score < 0:
    print('输入错误')
if score > 100:
    print('输入错误')

写法2：

score = int(input('input score: '))
if 90 <= score <= 100:
    print('A')
else:
    if 80 <= score < 90:
        print('B')
    else:
        if 60 <= score < 80:
            print('C')
        else:
            if 0 <= score < 60:
                print('D')
            else:     
                print('输入错误')

写法3：

score = int(input('input score: '))
if 90 <= score <= 100:
    print('A')
elif 80 <= score < 90:
    print('B')
elif 60 <= score < 80:
    print('C')
elif 0 <= score < 60:
    print('D')
else:
    print('输入错误')