python学习第十三天,内置函数

def func1():
    global list1
    list1 = [1,3]
    print(locals()) # 返回一个空字典
    print(globals()) # 返回所有全局变量,包括list1
print(list1) # 报错
func1()
print(list1) # 打印list1

print(a=1) #报错

print(*(1,2,3,‘a‘))
# 相当于:
print(1,2,3,‘a‘)

def func1(*args):
    print(*args)
func1(1,2,34)
#1 2 34
def func2(**kwargs):
    print(**kwargs)
func2(a=1)
#报错

print(1,2) # 1 2
print(1,2,3,sep=‘|‘) # 1|2|3

print(1,2,3,sep=‘|‘,end=‘哈哈哈‘) # end=‘‘
print(123)
#1|2|3哈哈哈123

print(12345,file=open(r‘a.txt‘,encoding=‘utf-8‘,mode=‘w‘))
#在没有该文件的情况下只能用a,w
#有文件可以用r+

dic = {1:‘ad‘,‘a‘:‘asd‘,‘1‘:‘as‘,2:‘adad‘}
print(hash(dic[1])) #-5305738840404791500
print(hash(dic[‘a‘]))
# 数字的hash值是数字本身(字典中的key除外)
a = 123
print(hash(a))
# 123

a = ‘10.1‘
print(int(a)) # 报错
b = 10.6
print(int(b)) # 10

int(a,8) # a 是八进制的数据

a = 5.5555
print(round(a))
# 6
b = 5.6666
print(round(b,3))
#5.667

print(pow(2,3))
# 相当于
print(2**3)

print(pow(2,3,5))
#幂对5的取余,相当于
print(2**3%5)

list1 = [1,2,3,4]
print(sum(list1)) # 初始值为0
print(sum(list1,100)) # 初始值为100

list1 = [1,2,3,‘4‘,‘5‘]
print(sum(int(i) for i in list1)) #默认初始值0
print(sum(int(i) for i in list1,100)) #设置初始值会报错

# key调用内置函数
min([1,-1,-3,1,4,5],key=abs)

# key调用自定义函数                                                
# 取values中最小值                                               
list1 = [(‘alex‘,1000),(‘taibai‘,18),(‘egon‘,19)]           
def func1(argv):                                            
    return argv[-1]                                         
print(min(list1,key=func1))                                 
                                                            

注意字典的取值
dic = {‘a‘:1,‘b‘:2,‘c‘:3}
def func1(argv): #--->只能接收一个参数
    return argv[1]
print(max(dic,key=func1)) #---->这样往里面传的是‘a‘,‘b‘,‘c‘
print(max(dic.items(),key=func1)) #----> 往里传的是 键值对

dic = {‘a‘:1,‘b‘:2,‘c‘:3}
for i in dic.items():
    print(i)
for j in dic.keys(): #== for j in dic:
    print(j)
for v in dic.values():
    print(v)

a = ‘1+2+3‘
print(eval(a))
#6

b = ‘[1,2,3,5]‘
print(eval(b),type(eval(b)))
#[1, 2, 3, 5]