python基础；if else;for;while 分支处理.continue,break

Posted 2020-12-01 flag_HW

if else

语法：

if <判断条件1>：

　　分支1

elif <判断条件2>：

　　分支2

else:

　　分支3

eg:

1 age = int(input("inpute you age"))
2 if age >= 18:
3     print("you are a person")
4 elif 6 <= age:
5     print("you are a child")
6 else:
7     print("you are a baby")

输出

12 you are a person

7 you are a child

4 you are a baby

 

while循环

语法1：while后判断条件成立时执行分支1，条件不成立则跳出循环继续向下执行。

while <判断条件>：

　　分支1

语法2：while没有被break且判断条件不为真会执行分支2。

while <判断条件>：

　　分支1

else:

　　分支2

count = 0
while count < 3:
    age = int(input("inpute you age"))
    if age > 56:
        print("you inpute bigger")
    elif age < 56:
        print("you inpute smaller")
    else:
        print("you got it")
        break
    count += 1
else:
    print("you trying more time")

 

for循环

语法1：循环体正常执行时，执行分支1；当循环体正常执行完且没有break则执行分支2.

for 循环体：

　　分支1

else:

　　分支2

 1 for i in range (3):
 2     age = int(input("inpute you age"))
 3     if age > 56:
 4         print("you inpute bigger")
 5     elif age < 56:
 6         print("you inpute smaller")
 7     else:
 8         print("you got it")
 9         break
10 else:
11     print("you trying more time")

 

continue break

语法：continue无条件结束本次循环，跳到下一次循环；break跳出整个循环

 1 for i in range(10):
 2     if i <= 5:
 3         print(i)
 4     elif i < 8:
 5         continue 
 6     elif i == 8:
 7         print("i = 8,break")
 8         break
 9     else:
10         print("this isn‘t print")