Why is rounding necessary to just get a result here?

Question

This is the code provided in the text analyzer section:

def count_char(text, char):
count = 0
for c in text:
if c == char:
count += 1
return count

filename = input("Enter a filename: ")
with open(filename) as f:
text = f.read()

for char in "abcdefghijklmnopqrstuvwxyz":
perc = 100 * count_char(text, char) / len(text)
print("{0} - {1}%".format(char, round(perc, 2)))

So, I understand that round(perc, 2) is supposed to round the result to 2 decimals.

What I don't understand is why simply deleting this part will not work. When I use this line of code:
print("{0} - {1}%".format(char))

I will receive an IndexError while I would be expecting to just receive an unrounded result.

Can anyone more experienced elaborate?

Answer 1

Your code doesn't work anymore because you deleted the whole information of the place holder. in the original, {0} refers to the variable char and {1} to round(perc,2), which is the variable perc rounded to 2 decimals. {1} doesn't have any content of you delete round(perc,2).

To have the result without rounding it, write format(char, perc).