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+ | ====== Python print函数用法,print 格式化输出 ====== | ||
+ | |||
+ | 使用print输出各型的 | ||
+ | - 字符串 | ||
+ | - 整数 | ||
+ | - 浮点数 | ||
+ | - 出度及精度控制 | ||
+ | |||
+ | <code python> | ||
+ | strHello = 'Hello Python' | ||
+ | print strHello | ||
+ | #输出结果:Hello Python | ||
+ | #直接出字符串 | ||
+ | </code> | ||
+ | |||
+ | ===== 1.格式化输出整数 ===== | ||
+ | python print也支持参数格式化,与C言的printf似, | ||
+ | <code python> | ||
+ | strHello = "the length of (%s) is %d" %('Hello World',len('Hello World')) | ||
+ | print strHello | ||
+ | #输出果:the length of (Hello World) is 11 | ||
+ | </code> | ||
+ | |||
+ | ===== 2.格式化输出16制整数 ===== | ||
+ | <code python> | ||
+ | nHex = 0x20 | ||
+ | #%x --- hex 十六进制 | ||
+ | #%d --- dec 十进制 | ||
+ | #%d --- oct 八进制 | ||
+ | |||
+ | print "nHex = %x,nDec = %d,nOct = %o" %(nHex,nHex,nHex) | ||
+ | |||
+ | #输出结果:nHex = 20,nDec = 32,nOct = 40 | ||
+ | #使用整数的各个制打印同一个数 | ||
+ | </code> | ||
+ | |||
+ | 如果需要输出二进制的话,可以使用python函数 bin() | ||
+ | |||
+ | <code> | ||
+ | Python 2.7.6 (default, Nov 10 2013, 19:24:18) [MSC v.1500 32 bit (Intel)] on win | ||
+ | 32 | ||
+ | Type "help", "copyright", "credits" or "license" for more information. | ||
+ | >>> bin(789) | ||
+ | '0b1100010101' | ||
+ | >>> | ||
+ | </code> | ||
+ | ===== 3.格式化输出浮点数(float) ===== | ||
+ | <code python> | ||
+ | import math | ||
+ | #default | ||
+ | print "PI = %f" % math.pi | ||
+ | #width = 10,precise = 3,align = left | ||
+ | print "PI = %10.3f" % math.pi | ||
+ | #width = 10,precise = 3,align = rigth | ||
+ | print "PI = %-10.3f" % math.pi | ||
+ | #前面填充字符 | ||
+ | print "PI = %06d" % int(math.pi) | ||
+ | |||
+ | #输出结果 | ||
+ | #PI = 3.141593 | ||
+ | #PI = 3.142 | ||
+ | #PI = 3.142 | ||
+ | #PI = 000003 | ||
+ | #浮点数的格式化,精度、度和 | ||
+ | </code> | ||
+ | |||
+ | ===== 4.格式化输出字符串(string) ===== | ||
+ | <code python> | ||
+ | #precise = 3 | ||
+ | print "%.3s " % ("jcodeer") | ||
+ | #precise = 4 | ||
+ | print "%.*s" % (4,"jcodeer") | ||
+ | #width = 10,precise = 3 | ||
+ | print "%10.3s" % ("jcodeer") | ||
+ | #输出结果: | ||
+ | #jco | ||
+ | #jcod | ||
+ | # jco | ||
+ | #同于字符串也存在精度、度和。 | ||
+ | </code> | ||
+ | |||
+ | ===== 5.输出列表(list) ===== | ||
+ | <code python> | ||
+ | l = [1,2,3,4,'jcodeer'] | ||
+ | print l | ||
+ | #输出结果:[1, 2, 3, 4, 'jcodeer'] | ||
+ | #于list直接打印即可 | ||
+ | '''6.出字典(dictionary)''' | ||
+ | d = {1:'A',2:'B',3:'C',4:'D'} | ||
+ | print d | ||
+ | #输出结果:{1: 'A', 2: 'B', 3: 'C', 4: 'D'} | ||
+ | #同python也是支持dictionary出的 | ||
+ | </code> | ||
+ | |||
+ | ===== 6.python print自动换行 ===== | ||
+ | print 会自动在行末加上回车,如果不需回车,只需在print语句的结尾添加一个逗号”,“,就可以改变它的行为。 | ||
+ | <code python> | ||
+ | for i in range(0,5): | ||
+ | print i, | ||
+ | </code> | ||
+ | |||
+ | 或直接使用下面的函数进行输出: | ||
+ | <code python> | ||
+ | sys.stdout.write("输出的字串") | ||
+ | </code> | ||
+ | |||
+ | ===== 7. 万能的 %r ===== | ||
+ | |||
+ | 有个同事问我python里面print "%r" 是什么用途,被问倒了。 | ||
+ | |||
+ | 用了这么些年的python,还没用过print %r。 | ||
+ | |||
+ | 网上查了一下,发现%r是一个万能的格式付,它会将后面给的参数原样打印出来,带有类型信息。 | ||
+ | |||
+ | ==== python print %r 案例 ==== | ||
+ | |||
+ | <code python> | ||
+ | formatter = "%r %r %r %r" | ||
+ | |||
+ | print formatter % (1, 2, 3, 4) | ||
+ | print formatter % ("one", "two", "three", "four") | ||
+ | print formatter % (True, False, False, True) | ||
+ | print formatter % (formatter, formatter, formatter, formatter) | ||
+ | print formatter % ( | ||
+ | "I had this thing.", | ||
+ | "That you could type up right.", | ||
+ | "But it didn't sing.", | ||
+ | "So I said goodnight." | ||
+ | ) | ||
+ | </code> | ||
+ | |||
+ | 输出结果: | ||
+ | |||
+ | <code> | ||
+ | $ python ex8.py | ||
+ | 1 2 3 4 | ||
+ | 'one' 'two' 'three' 'four' | ||
+ | True False False True | ||
+ | '%r %r %r %r' '%r %r %r %r' '%r %r %r %r' '%r %r %r %r' | ||
+ | 'I had this thing.' 'That you could type up right.' "But it didn't sing." 'So I said goodnight.' | ||
+ | $ | ||
+ | </code> | ||
+ | |||
+ | ===== 参考 ===== | ||
+ | * http://www.java-samples.com/showtutorial.php?tutorialid=1478 | ||
+ | |||