5.判断和循环

判断和循环

1 判断

1.1 判断的三种形式

1.2 判断的嵌套

2 循环

2.1 while循环

2.2 for循环

3 作业

3.1 输入年龄进行判断

3.2 打印偶数

3.3 猜年龄游戏

3.4 9*9乘法表

3.5 金字塔的打印

1 判断

1.1 判断的三种形式

1.if
2.if……else
3.if……elif……else

#直接if的语句
real_name ='xiaocao'
name = input('please enter the name:')
if name == real_name:
    print('congratulations!')

please enter the name:xiaocao
congratulations!

#if……else的语句
real_name ='xiaocao'
name = input('please enter the name:')
if name == real_name:
    print('congratulations!')
else:
    print('what a pity! Guess wrong')

please enter the name:xiaofang
what a pity! Guess wrong

# if……elif……else
real_age = 18
age = int(input("please enter the age"))
if age <18:
    print("sorry,guess younger")
elif age >18:
    print("sorry,guess older")
else:
    print('congratulations!')

please enter the age25
sorry,guess older

1.2 判断语句的嵌套

说白了就是一个if语句中又嵌套了一个if语句

# if……elif……else
real_age = 18
age = int(input("please enter the age"))
if age != 18:
    print("sorry,guess wrong")
    if age >18:
        print("sorry,guess older")
    else:
        print("sorry,guess younger")
else:
    print('congratulations!')

please enter the age25
sorry,guess wrong
sorry,guess older

2 循环

2.1 while循环

在循环中有两个比较重要的函数：

break和continue

break就是直接回到开始的地方

continue就是跳出这一步，后面继续

#while的循环好处就是可以直接将所需要的判断条件作为一个真实值增加break进行判断
real_age = 18
while True:
    age = int(input("please enter the age"))
    if age == 18:
        print('congratulations!')
        break
    else:
        print("sorry,guess wrong")
        if age >18:
            print("sorry,guess older")
        else:
            print("sorry,guess younger")
        

please enter the age23
sorry,guess wrong
sorry,guess older
please enter the age15
sorry,guess wrong
sorry,guess younger
please enter the age18
congratulations!

#循环中的continue的用法
num = 0
while num <=15:
    if num == 10:
        num +=1
        continue
    else:
        print(num)
    num+=1

0
1
2
3
4
5
6
7
8
9
11
12
13
14
15

2.1.1 while的嵌套

就是在一个while语句里面包含了另一个的while语句

# 注意，这里有几个循环终止的时候就需要几个break
real_age = 18

while True:
    age = int(input("please enter the age"))
    if age == 18:
        print('congratulations!')
        while True:
            prize_dict = {0:'toy_car',1:'doll',2:'puzzle'}
            print(f'please choose one of these gifts: {prize_dict}')
            prize = int(input('please enter the num:'))
            if prize == 1:
                print(f'Congratulations, you have received this gift,the gift is {prize_dict[1]}')
                break
            else:
                print("Sorry, we don't have this gift.Please reselect")
        break
                
    else:
        print("sorry,guess wrong")
        if age >18:
            print("sorry,guess older")
        else:
            print("sorry,guess younger")

please enter the age23
sorry,guess wrong
sorry,guess older
please enter the age15
sorry,guess wrong
sorry,guess younger
please enter the age18
congratulations!
please choose one of these gifts: {0: 'toy_car', 1: 'doll', 2: 'puzzle'}
please enter the num:2
Sorry, we don't have this gift.Please reselect
please choose one of these gifts: {0: 'toy_car', 1: 'doll', 2: 'puzzle'}
please enter the num:1
Congratulations, you have received this gift,the gift is doll

2.2 for循环

其实和while差不多，好处就是他不会溢出，知道位置便可以打印了

这个循环函数可以做一些效果出来

# 数据实例引用水导的知识点，我只是在慢慢学习啦
game_list = ['xiaoxiaokan','kaixinxiaoxiaole','tiaoyitiao','chaojimali','hundouluo','zhizhuzhipai','saolei','renzheshengui']

for i in game_list:
    print(i)

xiaoxiaokan
kaixinxiaoxiaole
tiaoyitiao
chaojimali
hundouluo
zhizhuzhipai
saolei
renzheshengui

2.2.1 for+break的方法

game_list = ['xiaoxiaokan','kaixinxiaoxiaole','tiaoyitiao','chaojimali','hundouluo','zhizhuzhipai','saolei','renzheshengui']

for i in game_list:
    if i == 'tiaoyitiao':
        break
    print(i)

xiaoxiaokan
kaixinxiaoxiaole

2.2.2 for+continue

game_list = ['xiaoxiaokan','kaixinxiaoxiaole','tiaoyitiao','chaojimali','hundouluo','zhizhuzhipai','saolei','renzheshengui']

for i in game_list:
    if i == 'tiaoyitiao':
        continue
    print(i)

xiaoxiaokan
kaixinxiaoxiaole
chaojimali
hundouluo
zhizhuzhipai
saolei
renzheshengui

2.2.3 for循环的嵌套

这个真的代码里面最常用，但是底层逻辑相对而言不是那么难

for i in range(3):
    for j in range(3):
        if i*j !=0:
            print(i*j)

1
2
2
4

2.2.4 for+else

for i in range(3):
    for j in range(3):
        if i*j !=0:
            print(i*j)
else:
    print('print finish')

1
2
2
4
print finish

3 作业

3.1 输入年龄进行判断

输入姑娘的年龄后，进行以下判断：
    1. 如果年龄小于18岁，打印“未成年”
    2. 如果年龄大于18岁小于40岁，打印“青年人”
    3. 如果年龄大于40岁小于60岁，打印“中年人”
    4. 如果年龄大于60岁，打印“老年人”

age = int(input('请输入年龄：'))
if age<0 or age >150:
    print('不属于年龄范围内的数字')
else:
    if age <= 18:
        print('未成年')
    elif age <=40:
        print('青年人')
    elif age <= 60:
        print('中年人')
    else:
        print('老年人')

请输入年龄：65
老年人

3.2 打印偶数

打印1-100之间的偶数

# fun 1
for i in range(1,101):
    if i %2 == 0:
        print(i,end = ' ')
        i+=1

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 

# fun 2
#这个代码多少有些麻烦，改一个版本
num = 1
while num <=100:
    if num % 2 == 1:
        num+=1
        continue
    else:
        print(num,end =' ')
        num+=1

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 

num = 1
while num<=100:
    if num % 2 == 0 :
        print(num,end =' ')
    num+=1

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 

3.3 猜年龄游戏

猜年龄游戏升级版，有以下三点要求：

1. 允许用户最多尝试3次
2. 每尝试3次后，如果还没猜对，就问用户是否还想继续玩，如果回答Y或y， 就继续让其猜3次，以此往复，如果回答N或n，就退出程序
3. 如果猜对了，就直接退出 

real_age = 18
chance = 1
while True:
    if chance <=3:
        age = int(input("please enter the age"))
        if age == 18:
            print('congratulations!')
            break               
        else:
            print("sorry,guess wrong")
            if age >18:
                print("sorry,guess older")
            else:
                print("sorry,guess younger")
    elif chance == 4:
        choice = input('please tell me to continue<<<')
        if choice == 'y'or choice =='Y':
            chance = 1
            continue
        else:
            break
    chance +=1

please enter the age23
sorry,guess wrong
sorry,guess older
please enter the age14
sorry,guess wrong
sorry,guess younger
please enter the age15
sorry,guess wrong
sorry,guess younger
please tell me to continue<<<y
please enter the age14
sorry,guess wrong
sorry,guess younger
please enter the age16
sorry,guess wrong
sorry,guess younger
please enter the age17
sorry,guess wrong
sorry,guess younger
please tell me to continue<<<n

3.4 打印乘法表

for i in range(1,10):
    for j in range(1,10):
        if i > j:
            print(f'{j}*{i}={i*j}',end=' ')
        elif i == j:
            print(f'{j}*{i}={i*j}',end = '\n')
        else:
            continue

1*1=1
1*2=2 2*2=4
1*3=3 2*3=6 3*3=9
1*4=4 2*4=8 3*4=12 4*4=16
1*5=5 2*5=10 3*5=15 4*5=20 5*5=25
1*6=6 2*6=12 3*6=18 4*6=24 5*6=30 6*6=36
1*7=7 2*7=14 3*7=21 4*7=28 5*7=35 6*7=42 7*7=49
1*8=8 2*8=16 3*8=24 4*8=32 5*8=40 6*8=48 7*8=56 8*8=64
1*9=9 2*9=18 3*9=27 4*9=36 5*9=45 6*9=54 7*9=63 8*9=72 9*9=81

# 上面的代码，貌似有些麻烦，看了别人的觉得我的可以更改一下
for i in range(1,10):
    for j in range(1,i+1):
        print(f'{i}*{j}={i*j}',end =' ')
    print()

1*1=1 
2*1=2 2*2=4 
3*1=3 3*2=6 3*3=9 
4*1=4 4*2=8 4*3=12 4*4=16 
5*1=5 5*2=10 5*3=15 5*4=20 5*5=25 
6*1=6 6*2=12 6*3=18 6*4=24 6*5=30 6*6=36 
7*1=7 7*2=14 7*3=21 7*4=28 7*5=35 7*6=42 7*7=49 
8*1=8 8*2=16 8*3=24 8*4=32 8*5=40 8*6=48 8*7=56 8*8=64 
9*1=9 9*2=18 9*3=27 9*4=36 9*5=45 9*6=54 9*7=63 9*8=72 9*9=81 

3.5 打印金字塔

'''
             # max_level=5
    *        # current_level=1，空格数=4，*号数=1
   ***       # current_level=2，空格数=3，*号数=3
  *****      # current_level=3，空格数=2，*号数=5
 *******     # current_level=4，空格数=1，*号数=7
*********    # current_level=5，空格数=0，*号数=9

# 数学表达式
空格数 = max_level-current_level
*号数 = 2*current_level-1
'''
max_level=int(input("请输入最大层数"))
for i in range(max_level):
  print(f'{" "*(max_level-i-1)}',end='')
  print(f'{"*"*(2*(i+1)-1)}')

请输入最大层数5
    *
   ***
  *****
 *******
*********

max_level = 5
for current_level in range(1,max_level+1):
    print(f'{(max_level-current_level)*" "}{(2*current_level-1)*"*"}')

    *
   ***
  *****
 *******
*********

max_level = 5
for current_level in range(1,max_level+1):
    space_num = max_level-current_level
    star_num = 2*current_level-1
    print(f'{(space_num)*" "}{(star_num)*"*"}')

    *
   ***
  *****
 *******
*********