python基础——流程控制

 if...else

user = "ss"
passwd = "abc"

username = input("name:")
password = input("password:")

if user == username:
    if passwd ==password:
        print("welcome~")
    else:
        print("password wrong")
else:
    print("username wrong")

if user == username and passwd == password:
    print("welcome~~")
else:
    print("wrong")

age = 12
guess_num = int(input("guess number:"))
if guess_num == age:
    print("got it")
elif guess_num > age:
    print("up")
else:
    print("down")

 

for循环

age = 12
for i in range(10):
    guess_num = int(input("guess number:"))
    if guess_num == age:
        print("got it")
        break
    elif guess_num > age:
        print("up")
    else:
        print("down")


a=['a','b','c']
for i in a:
    print(i)

 

while循环

n = 100
sum = 0
counter = 1

while counter <= n:
    sum = sum + counter
    counter += 1

print("1 到 %d 之和为: %d" % (n,sum))
print("\r")



#while … else
count = 0
while count < 5:
   print (count, " 小于 5")
   count = count + 1
else:
   print (count, " 大于或等于 5")
print("\r")



#while加判断
flag = 1
while (flag): print ('欢迎')
else: print("0")
print("\r")



#无限循环
while True:
   num = input("输入一个数字  :")
   #num = int(input("输入一个整数  :"))
   print ("你输入的数字是: ", num)
print("\r")

break　　跳出整个循环。

continue　　不再向下执行，跳回到循环开始处。

 

三元运算，if...else...的简写

if 1==1:
    name="aa"
else:
    name="bb"

name="aa" if 1==1 else "bb"