Python 3.4.4 学习笔记（004）python manuals/the python tutorial -- 3. An Informal Introduction to Python...

可以看到python版本号变了，找到一本学习python的书，Mark Lutz所著的Python学习手册，建议我直接学习最新版本的Python，到网站上看了一下，是3.5.1，但是不支持XP，能支持XP的是3.4.4，都是2015年12月发布的，果断更新。等漫游指南看完了，就转向那本学习手册。

学习运算符

/    除法，17/3 = 5.66...

//           17 // 3 = 5  整数除法

%           17 % 3 = 2  取余数

**           5 ** 2 = 25 乘方 这个和fortran 一样

交互模式下，最后一个表达式的值储存在变量"_"(下划线）里面

如：

>>> a=5 >>> b=4 >>> a*b 20 >>> _ 20
>>> b+_
24
>>> _
24
>>>

数值方面，除了int float还支持 Decimal 、Fraction，（小数分数） 复数

支持字符串，Strings， 单双引号都行

\' \" 分别表示 ’ “  转义字符的作用  \n 交互模式下原样输出，print函数作用下成为换行符

>>> print('C:\some\name') # here \n means newline! C:\some ame >>> print(r'C:\some\name') # note the r before the quote C:\some\name

三个双引号可以原样输出多行文本：

print("""\ Usage: thingy [OPTIONS]-h Display this usage message-H hostname Hostname to connect to """)

作用于字符串，n*"..." 或者 "。。。"*n表示将字符串重复n次，+则连接字符串。并排放置的字串自动连在一起，先连后乘（所乘数字置于最后，否则不合语法），先乘后加

>>> a= "abc" "def" "kk"*3 >>> a 'abcdefkkabcdefkkabcdefkk' >>> a="abc"+"def"+"kk"*3 >>> a 'abcdefkkkkkk' >>> >>> word = 'Python' >>> word[0] # character in position 0 'P' >>> word[5] # character in position 5 'n' >>> word[-1] # last character 'n' >>> word[-2] # second-last character 'o' >>> word[-6] 'P' >>> word[0:2] # characters from position 0 (included) to 2 (excluded) 'Py' >>> word[2:5] # characters from position 2 (included) to 5 (excluded) 'tho' >>> word[:2] + word[2:] 'Python' >>> word[:4] + word[4:] 'Python' >>> word[:2] # character from the beginning to position 2 (excluded) 'Py' >>> word[4:] # characters from position 4 (included) to the end 'on' >>> word[-2:] # characters from the second-last (included) to the end 'on'+---+---+---+---+---+---+| P | y | t | h | o | n |+---+---+---+---+---+---+0 1 2 3 4 5 6 -6 -5 -4 -3 -2 -1

看到以上这些，我只想说，太强大了

然后是列表，列表好像是数组，可是太灵活了

>>> squares = [1, 4, 9, 16, 25] >>> squares [1, 4, 9, 16, 25] >>> squares[0] # indexing returns the item 1 >>> squares[-1] 25 >>> squares[-3:] # slicing returns a new list [9, 16, 25] >>> squares[:] [1, 4, 9, 16, 25] >>> squares + [36, 49, 64, 81, 100] [1, 4, 9, 16, 25, 36, 49, 64, 81, 100] >>> cubes = [1, 8, 27, 65, 125] # something's wrong here >>> 4 ** 3 # the cube of 4 is 64, not 65! 64 >>> cubes[3] = 64 # replace the wrong value >>> cubes [1, 8, 27, 64, 125] >>> cubes.append(216) # add the cube of 6 >>> cubes.append(7 ** 3) # and the cube of 7 >>> cubes [1, 8, 27, 64, 125, 216, 343] >>> letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g'] >>> letters ['a', 'b', 'c', 'd', 'e', 'f', 'g'] >>> # replace some values >>> letters[2:5] = ['C', 'D', 'E'] >>> letters ['a', 'b', 'C', 'D', 'E', 'f', 'g'] >>> # now remove them >>> letters[2:5] = [] >>> letters ['a', 'b', 'f', 'g'] >>> # clear the list by replacing all the elements with an empty list >>> letters[:] = [] >>> letters [] >>> letters = ['a', 'b', 'c', 'd'] >>> len(letters) 4 >>> a = ['a', 'b', 'c'] >>> n = [1, 2, 3] >>> x = [a, n] >>> x [['a', 'b', 'c'], [1, 2, 3]] >>> x[0] ['a', 'b', 'c'] >>> x[0][1] 'b' >>> a="abcde" >>> a=[1,2,3,a,"b"] >>> a [1, 2, 3, 'abcde', 'b'] >>>

列表可以取元素，可以使用”+“，可以使用函数len()，可以追加元素，可以多维列表，可以不同变量类型放在一组

甚至这样也可以：

>>> a, b = 0, 1 >>> while b < 1000: ... print(b, end=',') ... a, b = b, a+b ... 1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,

感觉python就是一门外语有木有？

转载于:https://www.cnblogs.com/argent/p/5240698.html

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