01月22日【Python3 基础知识】

def add(string):
    total = 0
    numbers = []
    numbers += string.split("+")
    for num in numbers:
        total += int(num.strip())
    print("{0} = {1}".format(string, total))
#
def reduce(string):
    result = 0
    numbers = []
    numbers += string.split("-")
    result = int(numbers[0].strip())
    numbers.pop(0)
    for num in numbers:
        result -= int(num.strip())
    print("{0} = {1}".format(string, result))
#
def ride(string):
    total = 1
    numbers = []
    numbers += string.split("*")
    for num in numbers:
        total *= int(num.strip())
    print("{0} = {1}".format(string, total))
#
def division(string):
    result = 0
    numbers = []
    numbers += string.split("/")
    result = int(numbers[0].strip())
    numbers.pop(0)
    for num in numbers:
        result /= int(num.strip())
    print("{0} = {1}".format(string, result))
if __name__ == '__main__':
    print("##############################################")
    print("1: +法")
    print("2: -法")
    print("3: *法")
    print("4: /法")
    method = input("请选择: ")
    string = input("请输入:")
    if method == "1":
        add(string)
    elif method == "2":
        reduce(string)
    elif method == "3":
        ride(string)
    elif method == "4":
        division(string)
    else:
        print("输入错误")
    print("##############################################")

# 元组的元素不能修改
t = ('a', 'b', 3, 'b')
print(t)
print(t[0]) # 按下标输出元素
# index: 按元素输出下标
print(t.index('b'))     # 默认左往右
print(t.index('b', -1)) # 倒序查找
# count:统计字符个数
print(t.count('b'))

# 字典的定义:
d1 = dict(name = 'long', age = 30)
d2 = {'id':101, 'name':'longlong'}
d3 = dict([('name', 'long'), ('age', 20)])
print(d1)
print(d2)
print(d3)
# 方法
# get(key): 根据key获取value
# setdefault: 根据key获取value,如果key不存在,可以设定默认的value
print((d1.get('name')))
print(d1.setdefault('dizhi', 'guangxi'))
#
print(d1.keys())
print(d1.values())
#
for x, y in d1.items():
    print("{0}:{1}".format(x, y))
# update: 根据key更新valye;如果没有key则会添加该键值对
print(d1)
d1.update(d2)
print(d1)
# pop:根据key弹出value
print(d3.pop('name'))
print(d3)

# help： 方法解释
a = '123'
help(a.count)
# dir: 查看有什么方法可用
print(dir(a))
## type:  查看变量类型
print(type(a))
# len： 获取长度
print(len(a))
# isinstance: 判断变量是否某类型
print(isinstance(a, str))