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Name
liba2i - String-to-numeric library
Synopsis
Library to parse numbers from strings.
Description
Why?
Originally, we had atoi(3) and atol(3). Those APIs are not
inherently bad, but the implementations left the behavior
undefined when the input wasn't in range. They are also limited
to base 10.
Then came the strtol(3) family of functions. This API allows
checking for errors (overflow, trailing text, invalid base, and
no number at all). The method for reporting those errors isn't
exactly easy to check, though; it's very different to most
standard libc functions. Also, often one wants to parse a number
into a typedef, which might be narrower than the type returned by
strto*(3), or might be a signed or unsigned integer depending on
the system; and checking for overflow of that type (not the type
that strto*(3) returns) is very tricky.
Another problem is that strtoul(3) doesn't reject negative
values, which often results in bugs.
Then came strtonum(3) and later strtoi(3) and strtou(3) to the
BSDs. They considerably simplify the error checking, reporting
them via errno.
These new BSD functions are still problematic with typedefs whose
signedness may vary, and also don't reject negative values. And
they've had a bug which conceals range errors when there's
trailing text after the number.
What?
The functions provided by this library store the value via a
pointer, which adds some type safety: passing a pointer to a
different integer type would result in an error. The return
value is either 0 or -1, for success or error.
The functions for parsing unsigned integers reject negative
values, considering them underflow.
The type-generic macros allow use with typedefs, providing
appropriate range checks.
The short-hand versions of the functions and macros provide a
simple API (almost as simple as atoi(3)) with common defaults.
Files
INSTALL
Instructions for installing the library.
README
Main information about the project and the repository.
Makefile
share/mk/
Build system.
LICENSES/
share/licenses/
Licenses in use by the project.
etc/
Configuration files for (linter) programs called by the build system.
include/a2i/
Header files.
lib/pkgconfig/
Package configuration file. See pc(5) and pkgconf(1).
share/doc/
Project documentation.
share/man/
Manual pages.
src/a2i/
Source code.
Maintainers
Alejandro Colomar <alx@kernel.org> <https://www.alejandro-colomar.es/>
Copyright
LGPL-3.0-or-later WITH LGPL-3.0-linking-exception
See also
<https://www.alejandro-colomar.es/src/alx/alx/liba2i.git>
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