Python 随版本的不同,语法也有一些差异。 具体可以参考最新的Python帮助文档。 以下说明都是基于Python 3.1 版本。 一. Python 变量类型 #整型 integer_number = 90 #浮点 float_number = 90.4 #复数 complex_number = 10 + 10j #list 序列:列表、元组和字符串都是序列,序列的两个主要特点是索引操作符和切片操作符。 sample_list = [1,2,3,'abc'] #dictionary 字典 sample_dic = {"key":value, 2:3} #tuple 只读的序列 sample_tuple = (1,3,"ab") 二. Python 程序流程控制 2.1 条件判断结构 flag1 = some_value flag2 = other_value if flag1: do_function_1() elif flag2: do_function_2() else: do_function_3() 2.2 循环结构 for i in range(0, 10): print(i) for i in ['a','b','c','dd','eee']; print(i) 三. Print 函数及格式化输出 3.1 Print 自动换行 在Python 3.0 以后,Python 在print 函数上做了修改。 在Python 2.x 版本中,示例如下: for i in range(0,5): print i 默认情况是自动换行的,如果说是不自动换行,在最后加逗号就可以了:print i, 在Python 3.0 的文档里,对print 说明如下: print([object, ...], *, sep=' ', end='\n', file=sys.stdout) Print object(s) to the stream file, separated by sep and followed by end. sep, end and file, if present, must be given as keyword arguments. All non-keyword arguments are converted to strings like str() does and written to the stream, separated by sep and followed by end. Both sep and end must be strings; they can also be None, which means to use the default values. If no object is given, print() will just write end. The file argument must be an object with a write(string) method; if it is not present or None, sys.stdout will be used. 在Python 3.x 版本中,如果不想自动换行,就需要使用end 参数。该参数默认使用'\n',即回车换行,如果不想使用,换成其他字符,或者为空即可。 示例如下: >>> for i in range(5): print(i,end='') 01234 >>> for i in range(5): print(i) 0 1 2 3 4 >>> for i in range(5): print(i,end=',') 0,1,2,3,4, 3.2 print 正常输出 使用print输出各型的 (1). 字符串 (2). 整数 (3). 浮点数 (4). 出度及精度控制 >>> str = 'tianlesoftware oracle dba' >>> print(str); tianlesoftware oracle dba >>> 3.3 格式化输出整数 python print也支持参数格式化,与C言的printf似, 示例: >>> str = "the length of (%s) is %d" %('Hello World',len('Hello World')) >>> print(str) the length of (Hello World) is 11 或者直接写道print里: >>> print( "the length of (%s) is %d" %('Hello World',len('Hello World'))) the length of (Hello World) is 11 >>> 3.4 格式化输出16制整数 nHex = 0x20 #%x --- hex 十六进制 #%d --- dec 十进制 #%o --- oct 八进制 示例: >>> nHex = 0x20 >>> print("nHex = %x,nDec = %d,nOct = %o" %(nHex,nHex,nHex)) nHex = 20,nDec = 32,nOct = 40 3.5 格式化输出浮点数(float) #导入math 模块 >>> import math #default >>> print("PI = %f" % math.pi) PI = 3.141593 #width = 10,precise = 3,align = left >>> print("PI = %10.3f" % math.pi) PI = 3.142 #width = 10,precise = 3,align = rigth >>> print("PI = %-10.3f" % math.pi) PI = 3.142 #前面填充字符 >>> print("PI = %06d" % int(math.pi)) PI = 000003 >>> 3.6 格式化输出字符串(string) #precise = 3 >>> print("%.3s " % ("jcodeer")) jco #precise = 4 >>> print("%.*s" % (4,"jcodeer")) jcod #width = 10,precise = 3 >>> print ("%10.3s" % ("jcodeer")) jco 3.7 输出列表(list) #list直接打印即可 >>> l = [1,2,3,4,'tianlesoftware'] >>> print(l) [1, 2, 3, 4, 'tianlesoftware'] >>> print(l[0]) 1 >>> print(l[4]) tianlesoftware 3.8 输出字典(dictionary) >>> dave = {1:'A',2:'B',3:'C',4:'D'} >>> print(dave) {1: 'A', 2: 'B', 3: 'C', 4: 'D'} >>> print(dave[4]) D >>> print(dave[1]) A |
转载于:https://blog.51cto.com/zhonggupython/1022092