简单示例代码一

一、计数器

print("请选择算法运算符")
print('''
    1、加
    2、减
    3、乘
    4、除
''')


choice = input("请输入标号！")
num1 = int(input("请输入第一个数字"))
num2 = int(input("请输入第二个数字"))

if choice == '1':
    print(num1 + num2)
elif choice == '2':
    print(num1 - num2)
elif choice == '3':
    print(num1 * num2)
elif choice == '4':
    print(num1 / num2)
else:
    print("输入有误！！")

二、列表

computer = ["主机","显示器","鼠标","键盘"]
print(computer.index("主机"))
print(computer.count("显示器"))
computer.reverse()
print(computer)
computer.sort()
print(computer)
computer.append("u盘")
print(computer)
computer.insert(1,"耳机")
print(computer)
computer[1] = "蓝牙耳机"
print(computer)
computer.remove("蓝牙耳机")
print(computer)
print(computer[1:3])

computer = []
del computer

三、元组（元组与列表的差异在于元组中的元素不能修改）

computer = ("主机","显示器","鼠标","键盘")

print(computer.index("主机"))
print(computer.count("主机"))
print(computer[1:3])

四、集合(set)是无序，不重复，定义方法 set()函数或者大括号

computer = {"主机","显示器","鼠标","键盘"}
computer = set(["主机","显示器","鼠标","键盘"])
#列表去重
computer = ["主机","显示器","鼠标","键盘","主机","显示器"]
s= set(computer)
print(s)
s.add("耳机")
s.remove("显示器")
s.discard("蓝牙耳机")

a = set([1,2,3,4,5,6])
b = set([4,5,6,7,8,9])

print(a - b)
print(a & b)
print(a | b)
print(a != b)

五、字典 字段 key不重复

computer = {"主机":5000,"显示器":1000,"鼠标":500}
print(computer["主机"])
print(computer.get("主机",None))
print(computer.keys())
print(computer.values())
print(computer.items())

六、分支

age = int(input("请输入你的年龄"))

if age <= 7:
    print("儿童")
elif age > 7 and age < 18
    print("少年")
elif age >=18 and age < 65
    print("中年")
else
    print("老年")

七、循环

for n in range(1,5):
    print("第%s次种花" %n)


s = "123456"
for i in s:
    print(i)

computer = ["主机","显示器","鼠标","键盘"]
for i in computer:
    print(i,len(i))


computer = {"主机":5000,"显示器":1000,"鼠标":500}
for i in computer.items():
    print(i[0],i[1])

count = 0
while count <= 5:
    print(count)
    count += 1

for n in range(1,6):
    if n == 3:
      continue
    else:
       print(n)

for n in range(1,6):
    if n == 3:
        break
    else:
        print(n)

count = 0
while 1:
    if count < 3:
        name = input("请输入用户名").strip()
        if(len(name) == 0):
            print("输入不能为空")
            continue
        elif(name == 'xiaoming'):
            print("登录成功")
            break
        else:
            print("输入有误，重新输入")
            count += 1
    else:
        print("超过错误次数")
        break

八、文件操作

f = open("user.txt",'w+')
print(f.readline())
print(f.read())
f.write("zhaoliu 777777 guangdong")
f.flush()
f.close()

f = open('computer.txt')
for line in f:
    print(line)
f.close()

#异常与否，with执行完后关闭句柄

with open('computer.txt',encoding="utf8") as f:
    data = f.read()
    print(data)

九、函数

def hello():
    print("Hello world!")
hello()


def sum(a,b=2):
    return  a + b

print(sum(b=3,a=4))

def seq(n):
    result = []
    x = 0
    while x <= n:
        result.append(x)
        x += 1
    return  result
print(seq(9))

# *args 接受任意到元组 **kwargs 接受健值到字典
def sum2(*seq):
    x = 0
    for n in seq:
        x += n
    return  x

print(sum2(1,2,3))

def func(**computer):
    for k,v in computer.items():
        print("name:%s,price:%s" % (k,v))

print(func(zhuji=100,erji=200))

s = lambda a,b:a+b
print(s(3,4))