条件和循环

条件

if

age = input("请输入年龄:")

if int(age) < 18:
    print("未满18，再接再厉")
else:
    print("你已满18，可以自由玩耍了")

else...if...

age = int(input("请输入年龄:"))

if age<=6:
    print("童年")
elif age<=17:
    print("少年")
elif age <=40:
    print("青年")      
elif age <=65:
    print("中年")
elif age >65:
    print("老年")

pyhthon 还支持这种牛氓写法：

age = 18;

if  8<age<12 :
    print("8~12")
elif 12<age<19:
    print("19")  # 19

not:取反

if not 5>3:
    print("5<3")
else:
    print("5>3")

or:或者

a=1
b=-1

if a>0 or b>0 :
    print("a,b至少有一个大于0")

循环

for..in..

# for 项 in 序列:
#     代码块
fruits = ['apple','pear','orange']

for fruit in fruits:
    print(fruit)

while

count =0

while count<100 :
    print(count)
    count+=1

for x in range(start, stop[, step])

注意是左开右闭合[a,b)右边是取不到的

for x in range(3):
    print(x) # 0 1 2

for x in range(1,3):    
    print(x) # 1 2


for x in range(1,10,2):
    print(x) #1 3 5 7 9