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Python Python Basics Functions and Looping Functions

Francis Neal
Francis Neal
528 Points

Why // and not just / in the (num_of_char // 2) line?

Hi there,

In the line:

result = text + "!" * (num_of_char // 2)

Why do we need // and not just /? Just / returns the error:

result = text + "!" * (num_of_char / 2)
TypeError: can't multiply sequence by non-int of type 'float'

Thanks

Francis :-)

2 Answers

Steven Parker
Steven Parker
216,012 Points

The string (sequence) multiplying operation only works with an integer repeat count, but the normal division operator (/) always returns a float result which is not compatible.

Using the integer division operator instead (//) returns an integer result.
You could also use "int(num_of_char / 2)".

Martin Luckett
Martin Luckett
32,591 Points

(Originally added as comment rather than an answer - oops)

// is the floor division operator which is also sometimes called integer division and returns an integer whereas / may return a float (non-integer).

For example, 5 / 2 will return 2.5 (a float) where 5 // 2 will return 2 (an integer).

Multiplying text requires an integer as, for example, text plus "!" times 2.5 does not make sense.

It is a TypeError because the multiplication of sequences requires integers and using a single / can give a float.