已然好久没有在csdn上写文章了,这些系列文章是为了学习python而做的笔记
# -*- coding: utf-8 -*- # coding: utf-8 # 单行注释 ‘‘‘ 第一行 第二行 ‘‘‘ """ 多行注释 在python中 ‘ 和 " 都是一样的 """ # 连接行 str = ‘abcd‘ ‘efgh‘ print(str) str = ‘Hello \n World‘ print(str) str = """Hello World""" print(str) # 俩行 print(‘abc"123"efg‘) # abc"123"efg print("abc‘123‘efg") # abc‘123‘efg print(‘abc\‘123\‘efg‘) # abc‘123‘efg #----------------------------------# print(type([1, 2, 3, ‘a‘, ‘b‘])) # list print(type((1, ‘abc‘))) # tuple print(type(set([‘a‘, ‘b‘, 3]))) # set print(type({‘a‘:1, ‘b‘:2})) # dict def func(a, b, c): print(a, b, c) print(type(func)) # function a = func print(type(a)) # function import string print(string) # module # 类和类的实例 class MyClass(object): pass print(type(MyClass)) # type my_class = MyClass() print(my_class) # __main__.MyClass object at ox101caca10 # for 循环 for i in range(0, 30, 5): print(i) while 循环 a = 0 i = 1 while i<=100: a +=i i +=1 print(a) # 函数元组 def func_name(arg_1, arg_2): print(arg_1, arg_2) # (1, 2) return arg_1, arg_2 r = func_name(1, 2) print(type(r)) # tuple print(r[0], r[1]) def func(x, y=500): print(‘x=‘, x) print(‘y=‘, y) return x+y print(func(100)) print(func( y = 300, x = 200 )) print(func( x = 400)) def func(p): print(‘x=‘, p[‘x‘]) print(‘y=‘, p[‘y‘]) print(func({‘x‘:100, ‘y‘:200})) # 可变参数 *numbers是元组 会将后面的参数打包成一个只读数组 def func(name, *numbers): print(type(numbers)) print(numbers) func(‘Tom‘, 1, 2, 3, 4, ‘adb12‘, ‘d‘) def func(*args): print(args) print(type(args)) # tuple func(1, 2, 3, ‘a‘, ‘b‘, ‘c‘) func(‘x=‘, 100, ‘; y=‘, 200) # 字典 **kvs means key/values def func(name, **kvs) : print(name) print(type(kvs)) # dict print(kvs) func(‘Tom‘, china = ‘Beijing‘, uk = ‘London‘) # 可变参数必须放在后面 且 * 为必须带名字 def func(a, b, c, *, china, uk): print(china, uk) func(1, 2, 3, china = ‘BJ‘, uk = ‘LD‘) # 2.7.X 貌似不支持 def func(a, b, c=0, *args, **kvs): print(a, b, c) print(args) print(kvs) func(1, 2) func(1, 2, 3) func(1, 2, 3, ‘a‘, ‘b‘, ‘c‘) func(1, 2, 3, ‘a‘, ‘b‘, china = ‘BJ‘, uk = ‘LD‘) func(1, 2, 3, *(‘a‘, ‘b‘), **{‘china‘ : ‘BJ‘, ‘uk‘ : ‘LD‘}) # 递归问题 def my_sum(i): if i < 0 : raise ValueError elif i <= 1 : return i else : return i + my_sum(i-1) print(my_sum(1)) print(my_sum(5)) print(my_sum(500)) # f(n) = f(n-1) + f(n-2) def fib(n): if n < 1 : raise ValueError elif n <=2 : return 1 else : return fib(n-1) + fib(n-2) print(fib(40)) # 函数是可以作为参数 def sum(x, y, p = None ) : s = x + y if p: p(s) return s sum(100, 200) sum(100, 200, print) # can not run in python2.7x def cmp(x, y, cp = None) : if not cp : if x > y : return 1 elif x < y : return -1 else : return 0 else : return cp(x, y) def my_cp(x, y): if x < y : return 1 elif x == y : return 0 else : return -1 print(cmp(100, 200)) print(cmp(100, 200, my_cp)) print([1,2,3,4], sum) def do_sum(data , method): return method(data) print(sum([10, 20])) print(do_sum([1, 2, 3, 4], sum) ) # homework : change ‘ Hello, how are u? ‘ to ‘ u? are how ,Hello ‘ # 思路:先将单词逆序,再将整个句子逆序 def reverse(str_list, start, end): while(start < end): str_list[start], str_list[end] = str_list[end], str_list[start] start += 1 end -= 1 setence = ‘ Hello, how are u? ‘ str_list = list(setence) i = 0 while i < len(str_list): if str_list[i] != ‘ ‘: start = i end = start + 1 while (end < len(str_list)) and str_list[end] != ‘ ‘: end +=1 reverse(str_list, start, end - 1) i = end else: i += 1 str_list.reverse() print(‘‘.join(str_list))