Python 3.3 TypeError: unsupported operand type(s)

问题:

New to programming and am unsure why I am getting this error

count=int(input ("How many donuts do you have?"))
if count <= 10:
    print ("number of donuts: " ) +str(count)
else:
    print ("Number of donuts: many")

回答1:

In python3, print is a function that returns None. So, the line:

print ("number of donuts: " ) +str(count)

you have None + str(count).

What you probably want is to use string formatting:

print ("Number of donuts: {}".format(count))

回答2:

Your parenthesis is in the wrong spot:

print ("number of donuts: " ) +str(count)
                            ^

Move it here:

print ("number of donuts: " + str(count))
                                        ^

Or just use a comma:

print("number of donuts:", count)

回答3:

In Python 3 print is no longer a statement. You want to do,

print( "number of donuts: " + str(count) ) 

instead of adding to print() return value (which is None)