Python的基本操作——2.1 控制流-蒲公英云

Python的基本操作——2.1 控制流

桃扇骨 2021-09-27 04:00 347阅读 0赞

视频教程来自：www.zygx8.com，谢谢！

一、 If 语句

if 条件：
    语句1
elif 条件2：
    语句2
else
     语句3

范例：

# if-猜数字
number=66
guess=int(input('Enter an intenger: '))
if guess==number:
    print('you are right!')
elif guess<number:
    print('the number is higher than that')
else:
    print('the number is lower than that')

二、For 语句

# for语句
#1
for i in range(1,10):
    print(i)
else:
    print('done')
#2
a_list=[1,2,4,5,8]
for i in a_list:
    print(i)
#3
a_tuple=(2,3,5,6)
for i in a_tuple:
    print(i)
ano_tuple=('a','b','c')
for i in ano_tuple:
    print(i)
#4
a_dict={'Tom':11,"May":23}
for ele in a_dict:
    print(ele)
    print(a_dict[ele])

三、while 语句

# while 语句
number=66
flag=True
while flag:
    guess=int(input('Enter an intenger: '))
    if guess==number:
        print('you are right!')
        flag=False
    elif guess<number:
        print('the number is higher than that')
    else:
        print('the number is lower than that')
print('done!')

四、range 语句

# range 语句:range(1,10)，实际上是从1-9，包括前面不包括后面
# 同猜数字，限定次数时
number=66
chances=3 #3次机会
for i in range(1,chances+1):
    guess = int(input('Enter an intenger: '))
    if guess == number:
        print('you are right!')
        flag = False
    elif guess < number:
        print('the number is higher than that')
        print('you still have '+str(chances-i)+' chances')
    else:
        print('the number is lower than that')
        print('you still have ' + str(chances - i) + ' chances')
print('done!')

五、其他

break：跳出整个循环
continue：忽略循环剩下的部分，重新回到for的部分
pass：相当于什么都没有

pass
list1=[0,1,2]
for i in list1:
```
 if not i:
     continue
 print(i) 
```
i=0, if生效，执行continue，忽略循环体剩余部分，进入下一次循环i=1
i=1, if不满足，继续执行print；i=2时一样的道理
【注意】：python中，布尔型属于int，其实就是1-0
for i in list1:
```
 if not i:
     pass
 print(i)
```
i=0，if生效，执行pass，pass相当于什么都没有，所以继续执行print