Python基础

Posted 2020-11-09 hongrun

if语句

#if..else基本格式

if 条件:
    pass
else:
    pass

 

猜年龄

age_of_princal = 56

guess_age = int( input(">>:"))

if age_of_princal == guess_age :
    print("Yes,you got it..")
else:
    print("No,you are wrong")

View Code

 

#if..elif..else基本格式

if 条件:
    pass
elif 条件:
    pass
else:
    pass

 

#猜年龄

age_of_princal = 56

guess_age = int( input(">>:"))

if age_of_princal == guess_age:
    print("Good!")
elif guess_age > age_of_princal
    print("偏大")
else:
    print("偏小")

View Code

 

#判断分数级别

core = int(input("请输入你的分数："))

if core >= 90:
    print("A")
elif core >= 80:
    print("B")
elif core >= 70:
    print("C")
elif core >= 60:
    print("D")
else:
    print("滚")

View Code

 

#用户登录（不介意采用这种方法）

i = 1
name = "alex"
password = 12345

name1 = input("plese,Input you are name:")
password1 = input("please,input you are password:")

if i == 1:
    if name == str(name1):
        if password == int(password1):
            print("恭喜您成功登陆")
        else:
            print("您密码与之不符！您还有两次机会")
            name1 = input("plese,Input you are name:")
            password1 = input("please,input you are password:")
            if name == str(name1):
                if password == int(password1):
                    print("恭喜您成功登陆")
                else:
                    print("您密码与之不符！您还有一次机会")
                    name1 = input("plese,Input you are name:")
                    password1 = input("please,input you are password:")
                    if name == str(name1):
                        if password == int(password1):
                            print("恭喜您成功登陆")
                        else:
                            print("您密码与之不符！您没有机会了")
                            i = 0
                            exit(0)
                    else:
                        print("您用户名与之不符！您没有机会了")
                        i = 0
                        exit(0)
            else:
                print("您用户名与之不符！您还有一次机会")
                name1 = input("plese,Input you are name:")
                password1 = input("please,input you are password:")
                if name == str(name1):
                    if password == int(password1):
                        print("恭喜您成功登陆")
                    else:
                        print("您密码与之不符！您没有机会了")
                        i = 0
                        exit(0)
                else:
                    print("您用户名与之不符！您没有机会了")
                    i = 0
                    exit(0)
    else:
        print("您用户名与之不符！您还有两次机会")
        name1 = input("plese,Input you are name:")
        password1 = input("please,input you are password:")
        if name == str(name1):
            if password == int(password1):
                print("恭喜您成功登陆")
            else:
                print("您密码与之不符！您还有一次机会")
                name1 = input("plese,Input you are name:")
                password1 = input("please,input you are password:")
                if name == str(name1):
                    if password == int(password1):
                        print("恭喜您成功登陆")
                    else:
                        print("您密码与之不符！您没有机会了")
                        i = 0
                        exit(0)
                else:
                    print("您用户名与之不符！您没有机会了")
                    i = 0
                    exit(0)
        else:
            print("您用户名与之不符！您还有一次机会")
            name1 = input("plese,Input you are name:")
            password1 = input("please,input you are password:")
            if name == str(name1):
                if password == int(password1):
                    print("恭喜您成功登陆")
                else:
                    print("您密码与之不符！您没有机会了")
                    i = 0
                    exit(0)
            else:
                print("您用户名与之不符！您没有机会了")
                i = 0
                exit(0)
else:
    exit(0)

View Code

#用户登录（结合while循环&if..else）

name = "alex"
password = "123456"

i = 1
while i <= 3:
    user_name = input("Input you name:")
    user_password = input("Input you password:")
    if user_name == name:
        if user_password == password:
            print("Welcome!")
            break
        else:
            print("Input you password error")
            i += 1
    else:
        print("Input you name error")
        i += 1

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#判断最大与最小值

num1 = input("num1:")
num2 = input("num2:")
num3 = input("num3:")

if num1 > num2 > num3:
    print("最大值为：",num1,"最小值为：",num3)
elif num1 > num3 > num2:
    print("最大值为：", num1, "最小值为：", num2)
elif num2 > num1 > num3:
    print("最大值为：", num2, "最小值为：", num3)
elif num2 > num3 > num1:
    print("最大值为：", num2, "最小值为：", num1)
elif num3 > num1 > num2:
    print("最大值为：", num3, "最小值为：", num2)
else:
    print("最大值为：", num3, "最小值为：", num1)

View Code

#判断最大值

num1 = input("num1:")
num2 = input("num2:")
num3 = input("num3:")

if num1 > num2:
    max_num = num1
    if max_num > num3:
        print("Max NUM is",max_num)
    else:
        print("Max NUM is",num3)
else:
    max_num = num2
    if max_num > num3:
        print("Max NUM is",max_num)
    else:
        print("Max NUM is",num3)

View Code

---

while循环

#while基本格式

while 条件:
    pass

#输出1到10

num = 1

while num <= 10:
    print(num)
    num += 1;

View Code

#输出1到100的偶数（while循环&if..else嵌套）

num = 1

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

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#3次机会猜年龄（while循环&if..elif..else嵌套）

age = 50
guess_sum = 1
print("You can guess 3")
while guess_sum <= 3:
    user_input_age = int(input("Age is:"))

    if user_input_age == age:
        print("Yes")
        guess_sum = 4
    elif user_input_age > age:
        print("Is bigger")
        guess_sum += 1
    else:
        print("Is smaller")
        guess_sum += 1
print("End")

View Code

#一直猜年龄直到猜正确

age = 50

while True:
    user_input_age = int(input("Age is"))
    if user_input_age == age:
        print("Yes")
        break
    elif user_input_age > age:
        print("Is bigger")
    else:
        print("Is smaller")
print("End") #直到正确结束退出while循环执行

View Code

 

#while..else基本用法

while 条件:
    pass
else:#除了break其他情况都会出现
    pass

while循环中的else语句比较特殊，这里的else语句，只有在循环正常结束的时候才会执行，
什么意思呢？意思就是说如果我们的while循环在执行过程中中断了，也就是说执行了
break语句，这里的else语句就不会被执行。我们看一下下面的代码：

# 循环没有被中断
num = 0
while num<10:
    num = num + 1
    if num%2 ==0:
        continue
    print(num)
else:
    print("else-----")
结果：
1
3
5
7
9
else-----

---------------------------------------------------------------------------------------------------

# 循环被中断
num = 0
while num<10:
    num = num + 1
    if num%2 ==0:
        break
    print(num)
else:
    print("else-----")
结果：
1

#continue与else的使用

num = 1
while num <= 10:
    num += 1
    if num == 3:
        continue
    print(num)
else:#除了break其他情况都会出现
    print("This is else statement")

运行结果：

2
4
5
6
7
8
9
10
11

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end=""的使用

#end=""输出到同一行

print("hello world.",end="")
print("hello world.",end="")
print("hello world.",end="")

运行结果：

hello world.hello world.hello world.

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#根据用户输入值去输出矩形图

height = int(input("Height:"))
width = int(input("width:"))
num_height = 1

while num_height <= height:
    num_width = 1
    while num_width <= width:
        print("#",end = "")
        num_width += 1
    print()
    num_height += 1

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#输出#组成的直角三角形

num_height = 1

while num_height <= 4:
    num_width = 4
    while num_width - 3 <= num_height:
        print("#",end = "")
        num_width += 1
    print() #换行
    num_height += 1

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#第一种方式输出*号倒立直角三角形

user_width = int(input("please width:"))
user_height = int(input("please height:"))
i = 1

while i <= user_height:
    j = user_width
    while j - i>= 0:
        print("*",end="")
        j -= 1
    print()
    i += 1

View Code

#第二种方式输出*号倒立直角三角形

line = 5
while line > 0:
    tmp = line

    while tmp > 0:
        print("*",end="")
        tmp = tmp - 1
    print()
    line -= 1

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#九九乘法表倒立

first = 9

while first > 0:
    sec = 1
    while sec <= first:
        print(str(sec) + "*" + str(first) + "=" +str(sec * first), end = "\\t") #\\t是制表符，*空格
        sec += 1
    print()
    first -= 1

View Code

#输出九九乘法表

first = 1

while first <= 9:
    sec = 1
    while sec <= first:
        print(str(sec) + "*" + str(first) + "=" +str((sec) * first), end = "\\t")
        sec += 1
    print()
    first += 1

View Code

#字符格式化输出

name = input("name:")
age = input("age:")
job = input("job:")
salary = input("salary:")

if salary.isdigit(): #长得像不像数字，比如200d，‘200‘
    salary = int(salary)

else:
    #print("must input digit")
    exit("must input digit") #退出程序

msg = ‘‘‘
---------info of %s----------
Name : %s
Age : %s
Job : %s
Salary : %s
------------end--------------
‘‘‘ % (name,name,age,job,salary)

print(msg)

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for循环

#1-100所有的奇数

for i in range(1,101):
    if i % 2 != 0:
        print(i)

View Code

#第二种方法：1-100所有的奇数

for i in range(1,101,2): #2是步长
    print(i)

View Code

#循环100次，从50到70之间不打印

for i in range(100):
    if i >= 50 and i <= 70:
        continue
    else:
        print(i)

View Code

#第二种方式：循环100次，从50到70之间不打印

for i in range(100):
    if i < 50 or i >70:
        print(i)

View Code

#第一种方式：判断用户输入用户名和密码是否错误

_name = "alex"
_password = "123"

for i in range(3):
    user_name = input("You name:")
    user_password = input("You password:")
    if _name == user_name and _password == user_password:
        print("%s success login" %(user_name))
        break
    else:
        if i == 2:
            print("You have entered too many times.")
        print("You input name or password error!")

View Code

#第二种方式：判断用户输入用户名和密码是否错误

_name = "alex"
_password = "123"

for i in range(3):
    user_name = input("You name:")
    user_password = input("You password:")
    if _name == user_name and _password == user_password:
        print("%s success login" %(user_name))
        break #跳出，中断。break 过后，就不会执行最后面的else语句
    else:
        print("You input name or password error!")
else: #只要上面的for循环正常执行完毕，中间没被打断，就会执行else语句
   print("You have entered too many times.")

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#让用户输入一个值number，窗口输出1-number

number = int(input("从一到："))

for i in range(1,number + 1):
    print(i)

View Code

#输错三次后可以给用户选择是否继续

_name = "alex"
_password = "123"

counter = 0
while counter < 3:
    name = input("You name:")
    password = input("You password:")
    if name == _name and password == _password:
        print("Welcome %s login..." %_name)
        break
    else:
        print("invalid you name or password")
    counter += 1
    if counter == 3:
        keep_going_choice = input("还想玩么？[y/n]")
        if keep_going_choice == "y":
            counter = 0

else:
    print("error ")

View Code

#continue&break注意要点

exit_flag = False
for i in range(10):
    if i < 5:
        #continue
        print(i)
    print(end ="\\t")
    for j in range(10):
        if j < 5:
            #exit_flag = True
           # break #这个break能跳出 j这个循环
            continue
        print(j)
    if exit_flag:
        break #这个break能跳出 i 这个循环

列表

#索引切片

a = [‘wuchao‘,‘jinxing‘,‘xiaohu‘,‘sanpang‘,‘ligang‘]
print(a[1])#取到索引1的值
print(a[1:2])#取不到右边那个
print(a[1:])#取从索引1到最后
print(a[1:-1])#取从索引1到最后的前面一个
print(a[1:-1:1])#取从左到右一个一个去取
print(a[3::-2]) #从后面往前面步长为2

#添加append insert

a.append(‘xuepeng‘) #默认查到最后一个位置
print(a)
a.insert(1,‘xuepeng‘) #将数据插入到索引为1的位置
print(a)

#修改

a = [‘wuchao‘,‘jinxing‘,‘xiaohu‘,‘sanpang‘,‘ligang‘]
a[0] = ‘hongrun‘
print(a)

a[1:3] = [‘qingxia‘,‘jiaxin‘] #改索引为1,2的值
print(a)

#删除 remove pop del

a.remove(‘wuchao‘)#remove只能删除值，不能做切片
print(a)

b = a.pop(1) #pop根据索引取到值，还可以取到删除值
print(b)

del a[0] #del既可以删除一个值也可以删除整个对象del a
print(a)

#count计算某元素出现次数

a = [‘to‘,‘be‘,‘or‘,‘not‘,‘to‘,‘be‘].count(‘to‘) #计算a列表里有几个to
print(a)

#extend将列表添加到另一个列表里

a = [1,2,3]
b = [4,5,6]
a.extend(b)
print(a)
print(b)

运行结果：

[1, 2, 3, 4, 5, 6]
[4, 5, 6]

View Code

#index取出某个字符串的索引值

a = [‘wuchao‘,‘jinxing‘,‘xiaohu‘,‘sanpang‘,‘ligang‘]
t = a.index(‘jinxing‘)
print(t)

#index取出第二个ligang的索引值

a = [‘wuchao‘,‘jinxing‘,‘ligang‘,‘xiaohu‘,‘sanpang‘,‘ligang‘]
first_lg_index = a.index(‘ligang‘) #get the first ligang
little_list = a[first_lg_index + 1:] #切片第二个取小列表

second_lg_index = little_list.index("ligang")#取第二个ligang在小列表里的位置
print("second_lg_index",second_lg_index)

second_lg_index_in_big_list = first_lg_index + second_lg_index + 1 #通过第一个ligang和第二个ligang来计算出第二个ligang在大列表里的位置
print(second_lg_index_in_big_list)
print(a[first_lg_index + 1:])

#reverse将全部字符倒过来

a = [‘wuchao‘,‘jinxing‘,‘ligang‘,‘xiaohu‘,‘sanpang‘,‘ligang‘]
b = [‘luhongrun‘,‘luqingxia‘,‘lujiaxin‘]
c = a + b #a,b都不改变，得到一个全新的值
print(c)
a.reverse() #将a里列表的值顺序给倒过来了
print(a)

#sort默认数字由小到大与字母ASCII按顺序排序

x = [4,6,2,1,7,9]
x.sort()
print(x)
x.sort(reverse = True)#通过设置reverse的值为True，即可将数字由大到小排列与字母ASCII按从后到前排列
print(x)
b = sorted(x)
print(b)

#判断里面是否有haidilaoge

a = [‘wuchao‘,‘jinxing‘,‘ligang‘,‘xiaohu‘,‘sanpang‘,‘ligang‘]

print(a.count("haidilaoge"))

print("haidilaoge" in a)#in表示在不在a里面

运行结果：

0
False

#嵌套

a = [[1,2,3],‘alex‘,4,(2,3,4)]
b = a[0] #b = [1,2,3]
b[1] == 2
print(a[0][1])

运行结果：2

#第一种购物车（较麻烦）

user_salary = int(input("Please,Input you salary:"))
goods_list = [5800,9000,32,80,1500]
goods_name = ["iphone6s","mac-book","coffee","python-book","bicyle"]
goods_money = []
shopping_ = []
user_money_ye = []
i = 0
user_input = True
modle = ‘quit‘
user_money_ye.append(int(user_salary))
print("----------欢迎光临本店----------")
shopping_list = ‘‘‘1. iphone6s 5800,
2. mac book 9000,
3. coffee 32,
4. python book 80,
5. bicyle 1500‘‘‘
print(shopping_list)
print("--------------------------------")
while user_input:
    user_input_goods = input(">>>:")
    if user_input_goods != modle:
        if user_money_ye[i] >= goods_list[int(user_input_goods) - 1]:
            user_money = user_money_ye[i] - goods_list[int(user_input_goods) - 1]
            shopping_.append(goods_name[int(user_input_goods) - 1])
            goods_money.append(goods_list[int(user_input_goods) - 1])
            user_money_ye.append(user_money)
            i += 1
            print("以加入%s到您的购物车，当前余额%s" % (goods_name[int(user_input_goods) - 1], user_money_ye[i]))
        else:
            print("您余额不足，还剩%s" %user_money_ye[i])
            print("请重新选择")
    elif user_input_goods == modle:
        print("您已购买商品如下")
        #print(shopping_)
        g = 0
        for n in range(i):
            print(shopping_[g],end=‘\\t\\t\\t\\t‘)
            print(goods_money[g])
            g += 1
        print("您的余额为：%s" %user_money_ye[i])
        print("欢迎下次光临")
        user_input = False
    else:
        print("You input error!")

View Code

#第二种购物车

product_list = [(‘Mac‘,9000),
                (‘kindle‘,800),
                (‘tesla‘,900000),
                (‘python book‘,105),
                (‘bike‘,2000),]
shopping_car =[]
saving = input(‘please input your saving:‘)
if saving.isdigit():
    saving = int(saving)
    while True:
        for i,v in enumerate(product_list,1):#enumerate是加编号用的
            print(i,‘>>>>‘,v)
        choice = input(‘选择购买商品编号[退出:quit]:‘)
        if choice.isdigit():
            choice = int(choice)
            if choice > 0 and choice <= len(product_list):
                p_item = product_list[choice - 1]
                if p_item[1] < saving:
                    saving -= p_item[1]
                    shopping_car.append(p_item)
                else:
                    print(‘余额不足，还剩%s‘%saving)

            else:
                print(‘编码不存在‘)
        elif choice == ‘quit‘:
            print(‘--------------您已经购买如下商品----------------‘)
            for i in shopping_car:
                print(i)
            print(‘您还剩%s元钱‘%saving)
            break
        else:
            print(‘invalid input‘)
    for i in product_list:
        print(product_list.index(i),i)

View Code

 

---

序列

我们去银行办理业务都是需要排队的，排队前都是拿一个号，然后去排序，窗口叫到哪个号，哪个号就去窗口办理业务。

我们把排队的人想象成一个排列好的队伍，队伍按照号码来排序，他们是一个有序的队列。每个人排队的人都有名字，这些名字按照顺序排列起来也叫序列。同样，我们把人名替换成数字或字母，那他们也叫序列。

序列就是按照一定的顺序排列起来的一系列元素，每个元素不是在其他元素之前，就是在其他元素之后。

这里需要大家了解一条语句——range()。

range（）语句用来生成一组数字,在Pyhton2.x里可以很明显的看出来，Python3.x则看不出来（后面会解释原因）

>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] # 就像队伍一样，还是有按照顺序来排列的，每个元素不是在其他元素之前就是在其之后

>>> range(1,10)  # Range()生成的数字默认从0开始，也可以是指定起始值。取不到右边的10
[1, 2, 3, 4, 5, 6, 7, 8, 9]

>>> range(1,10,2)   # 还可以指定步长，这步长为2
[1, 3, 5, 7, 9]

# rang()的用法： 
range(stop) 
    #stop为结束位置，列出从0到stop之前的所有整数
    
range(start, stop[, step]) 
    #start表示起始数字,stop表示结束数字，stop表示每两个相邻数字之间的差，也叫步长
    #列出从start开始，到stop之前所有的数字

 参考：
http://www.cnblogs.com/resn/p/5776403.html