Python入门教程 控制流

控制流：一系列按顺序执行的指令

 

for(元素出现顺序迭代)

f = [1,3,6]
for i in f:
    print(i)
>>>
1
3
6

##字典遍历 键找值
d = {"a":1,"b":2}
for k in d:
    print(k,d[k])

>>>
a 1
b 2

##键值都返回
for k,v in d.item():
    print(k,v)
>>>
a 1
b 2

if

if int(input("Enter an inger : ")) == 1:
    print("yeah!")
>>>Enter an inger : 1
>>>yeah!

>>>Enter an inger : 2
>>>不符合就不操作

if int(input("Enter an inger : ")) == 1:
    print("yeah!")
else:
    print("Oops!")

>>>Enter an inger : 2
>>>Oops!

if i<10:
    print("i<10")
elif i<20:
    print("10<=i<=20")
elif:
    print(">=20")

while

a = 0
while a < 3:
    print(a)
    a+=1
>>>
0
1
2

break

f = [1,3,6]
for i in f:
    
    if i>5:
        break
    print(i)
>>>
1 
3
   

continue

f = [1,3,6]

for i in f:
    if i == 3:
        continue
    print(i)

range

range(5)
range(0,5)
list(range(5))
list(range(1,5,2))
##不到5

pass

class MyEmptyClass：
    pass

while False：
    pass

##什么都不做 占位

https://docs.python.org/3/tutorial/controlflow.html 2. https://python.swaroopch.com/control_flow.html