[issue46183] float function errors on negative number string with comma seperator ex: '-1, 234.0'

[Steven D'Aprano]

Steven D'Aprano <steve+python at pearwood.info> added the comment:

The behaviour is correct and not a bug. Commas are not supported when converting strings to float.

The allowed format for floats as strings is described in the docs:

https://docs.python.org/3/library/functions.html#float

By the way, the negative sign is irrelevant. Commas are not supported regardless of whether there is a negative sign or not.

The difficulty with commas is that it is ambiguous whether float('1,234') should interpret the comma as British/American digit grouping separator, and return 1234.0, or as the European decimal point, and return 1.234. For good or bad, Python has a bias towards English (like most programming languages) and so it chooses to only recognise the decimal point as a dot in the British/American style, and reject the comma.

If you want to support European-style commas as the decimal point, the easiest way is to call float('1,234'.replace(',', '.'))

----------
nosy: +steven.daprano
resolution:  -> not a bug
stage:  -> resolved
status: open -> closed

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue46183>
_______________________________________