Python学习---range/for/break/continue简单使用

range的使用：注意，在python3中，交互模式下已经不显示了

for循环的使用

打印50-70

# 第一种方案
for i in range(100):
    if i <= 70 and i >= 45:   #注意这里使用的是 and/or/not  非java中的&&，||,!
        print (i)
# 第二种方案
for i in range(50,71):
    print (i)

break/continue的使用

exit_Flag = False
for i in range(100):
    if i < 5:
        continue
    print("L_1:",i)
    for j in range(10):
        print("layer2:",j)
        if j == 7:
            exit_Flag=True
            break
    if exit_Flag:
        break

用户登录小程序

_user="hhh"
_pass="hello"
count = 1
while count <= 3:
    username = input("Please input the username:")
    password = input("Please input the password:")
    if _pass == password and _user == username:
        print("Welcome to BBT,", username)
        break
    else:
        print()
        print("Invalid username or password,you still have " + str(3 - count) + " times")
    count += 1
else:
    print("Time out,~-~")