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  • 内置函数

    
    
    # l = [4,1,5,2,7]
    # l1 = reversed(l)
    # print(l1)          # 保留原列表并返回一个反向的迭代器
    
    # slice类似切片
    # t = (123,32,1,34,56,122 )
    # sli = slice(1,5,2)
    # print(t[sli])
    # print(t[1:5:2])
    
    # print(format('aaa', '<33'))
    # print(format('aaa', '>33'))
    # print(format('aaa', '^33'))
    
    # 转换为bytes类型
    # print(bytes('你好',encoding='UTF-8'))   # unicode转换成utf-8的bytes
    # print(bytearray('你好',encoding='UTF-8'))   # 转换为bytearray类型,可修改里面
    
    # 查unicode
    # print(ord('1'))
    # print(ord('好'))
    # print(chr(88))
    
    # 查ascii
    # print(ascii('好'))
    # print(1)
    
    # print(all(['qwe','',True]))            # all只要为空,就返回false
    # print(all(['qwe']))
    # print(any(['qwe','',True]))            # any有一个为空就返回true
    
    # 拉链,根据最短的那个输出元祖
    # l = [1,2,3,4]
    # t = ('a','b',(1,2))
    # d = {'name':'chen',1:1}
    # for i in zip(l,t,d):
    #     print(i)                  #  (1, 'a', 'name'),(2, 'b', 1)
    
    
    # def is_old(n):
    #     return n % 2 == 1
    #
    # filter(function or None, iterable)  filter过滤,类似列表推导,只不过传入的是函数名和可迭代的
    # 该函数根据function参数返回的结果是否为真来过滤list参数中的项,filter只管筛选,不会改变原来的值
    # f = filter(is_old, [1,2,4,56,7,8,89])
    # print(f)
    # for i in f:
    #     print(i)
    
    
    # map两个参数一个是函数名,另一个是列表或元组,执行前后元素个数不变,值可能发生改变
    # m = map(abs, [1,-4,6,-8])
    # print(m)
    # for i in m:
    #     print(i)
    
    # def map_cheng(x):
    #     return x * x
    #
    # m = map(map_cheng, [1,2,3,4])
    # for i in m:
    #     print(i)
    
    # sorted生成新的列表而不改变原列表,占内存    l.sort()会改变
    # l = [-2,5,4,1,-78]
    # sort_l = sorted(l)
    # print(sort_l)
    # sort_l2 = sorted(l, key=abs,reverse=True)
    # print(sort_l2)
    
    
    
    # print(locals())
    # print(globals())
    
    # 迭代器 __next__()
    # next()
    # iter()
    
    # range(10)
    # print('__next__' in dir(range(1,11,2)))
    
    # dir 查看一个变量拥有的方法
    # print(dir([]))
    
    # 查看帮助文档
    # help(str)
    
    # f = open('w.py')
    # print(f.writable())
    
    # id()
    # hash 对于相同可hash数据的hash值在一次程序的执行过程中总是不变的(不可变数据类型)
    # print(hash(12345))
    # print(hash('sdfsdf'))
    
    # ret = input('input: ')
    
    # print('aaaaaaa',end='')  #指定输出的结束符,默认end='
    '回车
    # print('aaaaaaa',sep='')  #指定输出多个值之间的分隔符,这里输出一排a
    # print('aaaaaaa',file=f)  #写入到f.write()
    
    # exec('print(123)')     # 执行print,没有返回值
    # eval('print(123)')     # 有返回值
    
    # print(bin(3))           # 二进制
    # print(oct(10))          # 八进制
    # print(hex(10))          # 十六进制
    
    # print(abs(-34))           # 绝对值
    # print(divmod(7,2))          # 求结果和求余,返回元祖(3,1)
    # print(round(3.1333, 3))     # 3.133
    # print(pow(2,3))
    # print(pow(2,3,3))           #pow幂运算,再对3求余
    
    # print(sum([1,2,3,4]))
    # print(min([1,2,3,4]))
    # print(min((1,2,3,-4),key=abs))
    # print(max([1,2,3,4]))
    # print(max((1,2,3,-4),key=abs))
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  • 原文地址:https://www.cnblogs.com/hhsh/p/9563354.html
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