基础知识：if条件、while循环、fo

while True:
    name = input('请输入用户名：')
    psw = input('请输入密码：')
    if name =='seven' and psw == '123':
        print('登陆成功')
        break
    else:
        print('登陆失败')

input_times = 0
while input_times < 3:
    name = input('请输入用户名：').strip()
    pwd = input('请输入密码：').strip()
    if name == 'seven' and pwd == '123':
        print('登陆成功')
        break
    else:
        print('登陆失败')
        input_times += 1

input_times = 0
right_username = ['seven', 'alex']
while input_times < 3:
    name = input('请输入用户名：').strip()
    pwd = input('请输入密码：').strip()
    if name in right_username and pwd == '123':
        print('登陆成功')
        break
    else:
        print('登陆失败')
        input_times += 1

input_times = 0
while input_times < 3:
    name = input('请输入用户名：').strip()
    pwd = input('请输入密码：').strip()
    if (name == 'seven' or name == 'alex') and pwd == '123':
        print('登陆成功')
        break
    else:
        print('登陆失败')
        input_times += 1

x = 2
nums_1 = 0
while x < 101:
    if x % 2 == 0:
        nums_1 += x
    else:
        nums_1 -= x
    x += 1
print(nums_1)

#>>>>>>>51

x = 1
while x <= 12:
    if x == 6 or x == 10:
        pass
    else:
        print(x, end=(' '))
    x += 1

x = 1
while x <= 100:
    if x % 2 == 1:
        print(x)
    x += 1

x = 1
while x <= 100:
    if x % 2 == 0:
        print(x)
    x += 1

首先在内存开辟个新空间将值：123456存放进去，然后将它与变量名‘n1’关联在一起，也就是n1赋值给123456
然后再将n2赋值给n1，也就是原来的123456又关联了个变量名‘n2’。
我们都可以通过n1和n2访问到同一内存地址上的值：123456.
所以:n2和n1是相等关系，或者说print（n2 is n1）>>True

age_of_egon = 40
input_times = 1
while input_times <= 3:
    age = input('请输入年龄：').strip()
    input_times += 1
    if age.isdigit():
        age = int(age)
        if age == 40:
            print('恭喜')
            break
        else:
            print('猜错了')
    else:
        print('输入有误')

age_of_egon = 40
input_times = 1
while input_times <= 3:
    age = input('请输入年龄：').strip()
    input_times += 1
    if age.isdigit():
        age = int(age)
        if age == 40:
            print('恭喜')
            break
        elif input_times == 4:
            print('抱歉，错误次数太多，请10分钟后再试')
        else:
            print('猜错了')
    else:
        if input_times == 4:
            print('抱歉，错误次数太多，请10分钟后再试')
        else:
            print('输入有误，请输入数字')

age_of_egon = 40
input_times = 1
while input_times <= 3:
    age = input('请输入年龄：').strip()
    input_times += 1
    if age.isdigit():
        age = int(age)
        if age == 40:
            print('恭喜')
            break
        else:
            print('猜错了')
    else:
        print('输入有误')
    if input_times == 4:
        choice = input('是否继续（Y/N):')
        if choice == 'Y' or choice =='y':
            input_times = 1

for your_floor in range(1, 10):
    for i in range(1, your_floor + 1):
        print('%s*%s=%2s' % (i, your_floor, i * your_floor), end=(' '))
    print()

for i in range(1, 10):
    exp = ''
    for j in range(1, i+1):
        exp += '%s*%s=%2s ' % (j, i, i*j)
    print(exp)

for i in range(1, 10):
    for k in range(1, i):
        print(end='       ')
    for j in range(i, 10):
        print('%s*%s=%2s' % (i, j, i * j), end=' ')
    print()

for i in range(1, 10):
    exp = ''
    for k in range(1, i):
        exp += '       '
    for j in range(i, 10):
        exp += '%s*%s=%2s ' % (i, j, i * j)
    print(exp)

#一：
n = int(input('请输入打印的金字塔总层数：'))
for i in range(1, n+1):
    print(' '*(n-i)+'*'*(2*i-1))


# 二：
n = int(input('请输入打印的金字塔总层数：'))
for i in range(1, n+1):
    for s in range(1, n-i+1):
        print(' ', end='')
    for sta in range(1, 2*i):
        print('*')

x = 1
n = int(input('total floors:'))
for floor in range(1, n+1):
    star = '*' * x
    print(star.rjust(n + floor-1, ' '))
    x += 2
#rjust 字符右对齐：总共字符数：总层数+当前层数-1，第一层星为1个，以后+2递增，其余用空格补全。

x = 1
n = int(input('total floors:'))
for floor in range(1, n+1):
    star = '*' * x
    print(star.center(2*n-1, ' '))
    x += 2