Python格式化字符串(格式化输出)_python字符和数字转换

从Python2.6开始，有一个替代方法：方法str.format()。下面是一些使用现有字符串格式运算符(%)的示例：>>> “Name: %s, age: %d” % (‘John’, 35)

‘Name: John, age: 35’

>>> i = 45

>>> ‘dec: %d/oct: %#o/hex: %#X’ % (i, i, i)

‘dec: 45/oct: 055/hex: 0X2D’

>>> “MM/DD/YY = %02d/%02d/%02d” % (12, 7, 41)

‘MM/DD/YY = 12/07/41’

>>> ‘Total with tax: $%.2f’ % (13.00 * 1.0825)

‘Total with tax: $14.07’

>>> d = {‘web’: ‘user’, ‘page’: 42}

>>> ‘http://xxx.yyy.zzz/%(web)s/%(page)d.html’ % d

‘http://xxx.yyy.zzz/user/42.html’

以下是等效的代码片段，但使用str.format()：>>> “Name: {0}, age: {1}”.format(‘John’, 35)

‘Name: John, age: 35’

>>> i = 45

>>> ‘dec: {0}/oct: {0:#o}/hex: {0:#X}’.format(i)

‘dec: 45/oct: 0o55/hex: 0X2D’

>>> “MM/DD/YY = {0:02d}/{1:02d}/{2:02d}”.format(12, 7, 41)

‘MM/DD/YY = 12/07/41’

>>> ‘Total with tax: ${0:.2f}’.format(13.00 * 1.0825)

‘Total with tax: $14.07’

>>> d = {‘web’: ‘user’, ‘page’: 42}

>>> ‘http://xxx.yyy.zzz/{web}/{page}.html’.format(**d)

‘http://xxx.yyy.zzz/user/42.html’

与Python2.6+一样，所有Python3发行版(到目前为止)都了解如何同时执行这两种操作。我不知羞耻地把这些东西直接从my hardcore Python intro book和介绍+中间Python courses I offer的幻灯片中撕了出来。:-)

2018年8月更新：当然，现在我们有了the f-string feature in 3.6，我们需要的等价示例，即，是的，另一种选择：>>> name, age = ‘John’, 35

>>> f’Name: {name}, age: {age}’

‘Name: John, age: 35’

>>> i = 45

>>> f’dec: {i}/oct: {i:#o}/hex: {i:#X}’

‘dec: 45/oct: 0o55/hex: 0X2D’

>>> m, d, y = 12, 7, 41

>>> f”MM/DD/YY = {m:02d}/{d:02d}/{y:02d}”

‘MM/DD/YY = 12/07/41’

>>> f’Total with tax: ${13.00 * 1.0825:.2f}’

‘Total with tax: $14.07’

>>> d = {‘web’: ‘user’, ‘page’: 42}

>>> f”http://xxx.yyy.zzz/{d[‘web’]}/{d[‘page’]}.html”

‘http://xxx.yyy.zzz/user/42.html’