Python for循环返回NaN而不是字符串输出

Question

def numberToText(number):
     if number == 1:
         return('one')
     elif number == 2:
         return('two')
     elif number == 3:
         return('three')
     elif number == 4:
         return('four')
     elif number == 5:
         return('five')
     elif number == 6:
         return('six')
     elif number == 7:
         return('seven')
     elif number == 8:
         return('eight')
     elif number == 9:
         return('nine')
     elif number == 10:
         return('ten')

def tenGreenBottles():
  print ("How many bottles to start with?")
  bottles = int(input())
  for i in range (bottles, 0, -1):
      print "%g green bottles, hanging on the wall" %numberToText(i)
      print "%g green bottles, hanging on the wall" %numberToText(i)
      print "and if one green bottle, should accidentally fall"
      bob = i - 1
      print "there'd be %g green bottles." %numberToText(bob)
      print

I have been playing around with this code for a while and no matter what I do the For Loop prints out NaN instead of the string. The function numberToText works as intended when I use the For Loop with out the string formatting.

Answer 1

You should try this instead:

 print "{} green bottles, hanging on the wall".format(numberToText(i))

My Reasoning for Recommending format

Originally, in Python the common way to perform string interpolation (which is what we're talking about here) was to use format strings (such as %s , %d , or %g ) and a format operator between your string and the things that were to be inserted into it.

However, you have to use the correct format string for the kind of thing you want to interpolate.

For instance, to insert a string into another string, you use %s :

>>> print "%s green bottles, hanging on the wall" % "fifteen"
fifteen green bottles, hanging on the wall

However, if you have a number you wish to interpolate, you would typically use %d :

>>> print "%d green bottles, hanging on the wall" % 15
15 green bottles, hanging on the wall

If you make a mistake, you get an error:

>>> print "%d green bottles, hanging on the wall" % "15"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: %d format: a number is required, not str

You seemed like you are new to Python, so I recommend just using format instead, which is a newer and more powerful way to perform string interpolation:

 >>> print "{} green bottles, hanging on the {}".format(20, "balcony")
 20 green bottles, hanging on the balcony

When you get more comfortable with string interpolation, you can try to do more advanced stuff with format . You will probably never need to use % again to perform string interpolation. I recommend just trying to focus on and remember format .