if語句

判斷使用者名稱和密碼是否正確：

_username="liulu"
_password="123456"

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

if username==_username and password==_password:
    print("welcome {name} login...".format(name=username))
else:
    print("invalid username and password!")


猜年齡：

my_age=23

guess_age=int(input("please guess my age:")) #因為input預設的是字串，所以需要int

if guess_age==my_age:
    print("you got it!")
elif guess_age>my_age:
    print("think smaller...")
else:
    print("think bigger...")


while迴圈
猜年齡，最多猜三次，猜不中不能再猜

my_age=23

count=0

while True:        #True要大寫                #可以簡化為while count <3:
    if count==3:
        break
#break 可結束執行本次迴圈。continue是跳出本次迴圈。

    guess_age=int(input("guess age:"))

    if guess_age==my_age:
        print("you got it")
        break
    elif guess_age>my_age:
        print("think smaller...")
    else:
        print("think bigger...")

    count+=1

else:
    print("you have no more chance to guess...")


for迴圈
猜年齡，最多猜三次，猜不中不能再猜

my_age=23

for i in range(3)

    guess_age=int(input("guess age:"))

    if guess_age==my_age:
        print("you got it")
        break
    elif guess_age>my_age:
        print("think smaller...")
    else:
        print("think bigger...")

else:
    print("you have no more chance to guess...")

步長
 

# 從0到10
for i in range(10):
    print("loop",i)

# 只打02468
for i in range(0,10,2):
    print("loop",i)

if 與 while 混合使用案例：

猜年齡，最多猜三次，猜不中詢問是否繼續猜，輸入n後不再猜。

my_age=23

count=0

while count<3:

    guess_age=int(input("guess age:"))

    if guess_age==my_age:
        print("you got it")
        break
    elif guess_age>my_age:
        print("think smaller...")
    else:
        print("think bigger...")

    count+=1

    if count==3:
        continue_confirm=input("would you like to keep guessing?")
        if continue_confirm!="n":
            count=0


for迴圈巢狀

for i in range(10):
    print("------",i)
    for j in range(10):
        print(j)
        if j>5:
            break