一、if-else流程判断
1、判断输入的用户名密码是否正确’
#首先保存用户名和密码
_username = ‘leilu‘
_password = ‘123456‘
#输入用户名密码
username = input("username:")
password = input("password:")
#做判断
if _username == username and _password == password:
print("Welcome user {name} login..." .format(name=username))
else:
print("Invalid username or password!")
2、猜老男孩的年龄
age_of_oidboy =56
guess_age = int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes,you got it !")
elif guess_age > age_of_oldboy:
print("think smaller...")
else:
print("think bigger...")
二、while循环
1、计数：从0到1000
count = 0
while Ture:
print("count:", count)
count = count + 1 #count +=1
if count == 1000:
break
2、猜老男孩的年龄，三次猜不对就退出
age_of_oidboy =56
count = 0
while Ture:
if count == 3:
break
guess_age = int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes,you got it !")
break
elif guess_age > age_of_oldboy:
print("think smaller...")
else:
print("think bigger...")
count +=1
优化：
age_of_oidboy =56
count = 0
while count < 3:
guess_age = int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes,you got it !")
break
elif guess_age > age_of_oldboy:
print("think smaller...")
else:
print("think bigger...")
count +=1
else:
print("you have tried too many times.")
3、猜老男孩的年龄，三次才不对询问要不要继续猜，输入n代表退出，其他任意键代表继续
age_of_oidboy =56
count = 0
while count < 3:
guess_age = int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes,you got it !")
break
elif guess_age > age_of_oldboy:
print("think smaller...")
else:
print("think bigger...")
count +=1
if count == 3:
countine_confirm = input("do you want to keep guessing...")
if countine_confirm != ‘n‘ :
count = 0
三、for循环
1、打印0到9，默认步长为1
for i in range(10):
print("loop" ,i)
2、隔一个打印
for i in range(0,10,2):
print("loop" ,i)
3、猜老男孩的年龄，三次猜不对就退出
age_of_oidboy =56
for i in range(3):
guess_age = int(input("guess age:"))
if guess_age == age_of_oldboy:
print("yes,you got it !")
break
elif guess_age > age_of_oldboy:
print("think smaller...")
else:
print("think bigger...")
else:
print("you have tried too many times.")
四、循环嵌套
for i in range(10):
print(‘------------‘ ,i)
for j in range(10):
print(j)
if j > 5
break
break：结束整个循环
continue：结束本次循环
原文：https://www.cnblogs.com/leilu/p/10453116.html