python基礎1—零碎

已然好久沒有在csdn上寫文章了，這些系列文章是爲了學習python而做的筆記 

# -*- coding: utf-8 -*-
# coding: utf-8

# 單行註釋

'''
第一行
第二行
'''

"""
多行註釋
在python中 ' 和 " 都是一樣的
"""

# 連接行
str = 'abcd' \
	   'efgh'
print(str)

str = 'Hello \n World'
print(str) 

str = """Hello
World"""
print(str)                      # 倆行  


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

# 類和類的實例
class MyClass(object):
	pass
print(type(MyClass))  	# type
my_class = MyClass()
print(my_class)			# __main__.MyClass object at ox101caca10

#  for 循環
for i in range(0, 30, 5):
	print(i)


while 循環
a = 0
i = 1
while i<=100:
	a +=i
	i +=1
print(a)	


#  函數元組
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}))

# 可變參數   *numbers是元組 會將後面的參數打包成一個只讀數組
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')

# 可變參數必須放在後面 且 * 爲必須帶名字
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'})


# 遞歸問題
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))

#  函數是可以作爲參數
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：先將單詞逆序，再將整個句子逆序
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))

I'm fish, I'm on.