python - 字符串中的变量，python 2.7

Question

通常，我可以使用下面的代码实现一个字符串内的变量

print "this is a test %s" % (test)

然而，它似乎不起作用，因为我不得不使用它

from __future__ import print_function

Answer 1

>>> test = '!'
>>> print "this is a test %s" % (test)
this is a test !

如果您导入 print_function 功能，print 充当函数:

>>> from __future__ import print_function
>>> print "this is a test %s" % (test)
  File "<stdin>", line 1
    print "this is a test %s" % (test)
                            ^
SyntaxError: invalid syntax

您应该在导入后使用函数调用形式。

>>> print("this is a test %s" % (test))
this is a test !

边注

根据 the documentation :

str.format is new standard in Python 3, and should be preferred to the % formatting.

>>> print("this is a test {}".format(test))
this is a test !