When using the old style of string formatting in python, ie, "" % (), if the thing after the percent is a tuple, python tries to break it down and pass individual items in it to the string. For example,
tup = (1,2,3)
print("this is a tuple %s" % (tup))This will give the output:
TypeError: not all arguments converted during string formatting
This is because of the reason mentioned above. If you want to pass a tuple, you need to create a wrapping tuple using the (tup, ) syntax. For example,
tup = (1,2,3)
print("this is a tuple %s" % (tup, ))This will give the output:
this is a tuple (1, 2, 3)
The (tup,) notation differentiates a single-valued tuple from an expression.