The `j` function uses `r` to accumulate its result, but did not declare it with auto, causing the caller's value to be clobbered. To fix this, declare `r` as auto to make it a local variable.
|2 years ago|
|gen||2 years ago|
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|karatsuba.py||2 years ago|
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For more information, see this
bc's full manual.
bc also includes an implementation of
dc in the same binary, accessible
via a symbolic link, which implements all FreeBSD and GNU extensions. (If a
dc binary is desired,
bc can be copied and renamed to
! command is omitted; I believe this poses security concerns and that such
functionality is unnecessary.
For more information, see the
dc's full manual.
bc is Free and Open Source Software (FOSS). It is offered under the BSD
2-clause License. Full license text may be found in the
bc only requires a C99-compatible compiler and a (mostly) POSIX
2008-compatible system with the XSI (X/Open System Interfaces) option group.
Since POSIX 2008 with XSI requires the existence of a C99 compiler as
POSIX and XSI-compatible system will have everything needed.
Systems that are known to work:
- Mac OSX
- Solaris* (as long as the Solaris version supports POSIX 2008)
Please submit bug reports if this
bc does not build out of the box on any
system besides Windows. If Windows binaries are needed, they can be found at
bc should build unmodified on any POSIX-compliant system.
For more complex build requirements than the ones below, see the build manual.
It is possible to download pre-compiled binaries for a wide list of platforms,
including Linux- and Windows-based systems, from xstatic. This link always
points to the latest release of
For the default build with optimization, use the following commands in the root directory:
./configure.sh -O3 make
To only build
bc, use the following commands:
./configure.sh --disable-dc make
To only build
dc, use the following commands:
./configure.sh --disable-bc make
For debug builds, use the following commands in the root directory:
./configure.sh -g make
To install, use the following command:
dc will be installed in
/usr/local. For installing in
other locations, use the
PREFIX environment variable when running
configure.sh or pass the
--prefix=<prefix> option to
configure.sh. See the
build manual, or run
./configure.sh --help, for more details.
Package and Distro Maintainers
When I ran benchmarks with my
bc compiled under
clang, it performed much
better than when compiled under
gcc. I recommend compiling this
I also recommend building this
bc with C11 if you can because
bc will detect
a C11 compiler and add
_Noreturn to any relevant function(s).
I wrote this
bc with Separation of Concerns, which means that there are many
small functions that could be inlined. However, they are often called across
file boundaries, and the default optimizer can only look at the current file,
which means that they are not inlined.
Thus, because of the way this
bc is built, it will automatically be slower
bc implementations when running scripts with no math. (My
math is much faster, so any non-trivial script should run faster in my
Some, or all, of the difference can be made up with the right optimizations. The optimizations I recommend are:
in that order.
Link-time optimization, in particular, speeds up the
bc a lot. This is because
when link-time optimization is turned on, the optimizer can look across files
and inline much more heavily.
However, I recommend NOT using
-march=native. Doing so will reduce this
bc's performance, at least when building with link-time optimization. See the
benchmarks for more details.
By default, non-debug binaries are stripped, but stripping can be disabled with
-T option to
bc as an Alternative
bc is packaged as an alternative to an already existing
it is possible to rename it in the build to prevent name collision. To prepend
to the name, just run the following:
To append to the name, just run the following:
If a package maintainer wishes to add both a prefix and a suffix, that is allowed.
Note: The suggested name (and package name) when
bc is not available is
Package and distro maintainers have one tool at their disposal to build this
bc in the optimal configuration:
This script is not a compile-time or runtime prerequisite; it is for package and distro maintainers to run once when a package is being created. It finds the optimal Karatsuba number (see the algorithms manual for more information) for the machine that it is running on.
The easiest way to run this script is with
If desired, maintainers can also skip running this script because there is a sane default for the Karatsuba number.
bc is robust.
It is well-tested, fuzzed, and fully standards-compliant (though not certified)
bc. The math has been tested with 40+ million random problems, so
it is as correct as I can make it.
bc can be used as a drop-in replacement for any existing
is also compatible with MinGW toolchains, though history is not supported on
In addition, this
bc is considered complete; i.e., there will be no more
releases with additional features. However, it is actively maintained, so if
any bugs are found, they will be fixed in new releases. Also, additional
translations will also be added as they are provided.
Comparison to GNU
bc compares favorably to GNU
- It has more extensions, which make this
bcmore useful for scripting.
bcis a bit more POSIX compliant.
- It has a much less buggy parser. The GNU
bcwill give parse errors for what is actually valid
bccode, or should be. For example, putting an
elseon a new line after a brace can cause GNU
bcto give a parse error.
bchas fewer crashes.
bccalculates the wrong number of significant digits for
bcwill sometimes print numbers incorrectly. For example, when running it on the file
tests/bc/power.txtin this repo, GNU
bcgets all the right answers, but it fails to wrap the numbers at the proper place when outputting to a file.
bcis faster. (See Performance.)
bc packs more than
1 decimal digit per hardware integer, this
bc is faster than GNU
bc and can be much faster. Full benchmarks can be
found at manuals/benchmarks.md.
There is one instance where this
bc is slower: if scripts are light on math.
This is because this
bc's intepreter is slightly slower than GNU
that is because it is more robust. See the benchmarks.
To see what algorithms this
bc uses, see the algorithms manual.
bc only has support for English (and US English), French,
German, Portuguese, Dutch, Polish, Russian, Japanese, and Chinese locales.
Patches are welcome for translations; use the existing
*.msg files in
locales/ as a starting point.
In addition, patches for improvements are welcome; the last two messages in Portuguese were made with Google Translate, and the Dutch, Polish, Russian, Japanese, and Chinese locales were all generated with DeepL.
The message files provided assume that locales apply to all regions where a
language is used, but this might not be true for, e.g.,
Any corrections or a confirmation that the current texts are acceptable for
those regions would be appreciated, too.
Other projects based on this bc are:
bc. The busybox maintainers have made their own changes, so any bugs in the busybox
bcshould be reported to them.
bc. The maintainer has also made his own changes, so bugs in the toybox
bcshould be reported there.
bc is written in pure ISO C99, using POSIX 2008 APIs.
bc uses the commit message guidelines laid out in this blog post.
bc uses semantic versioning.
Items labeled with
(maintainer use only) are not included in release source
.gitignore The git ignore file (maintainer use only). .travis.yml The Travis CI file (maintainer use only). codecov.yml The Codecov file (maintainer use only). configure A symlink to configure.sh to make packaging easier. configure.sh The configure script. functions.sh A script with functions used by other scripts. install.sh Install script. karatsuba.py Script to find the optimal Karatsuba number. LICENSE.md A Markdown form of the BSD 2-clause License. link.sh A script to link dc to bc. locale_install.sh A script to install locales, if desired. locale_uninstall.sh A script to uninstall locales. Makefile.in The Makefile template. manpage.sh Script to generate man pages from markdown files. NOTICE.md List of contributors and copyright owners. RELEASE.md A checklist for making a release (maintainer use only). release.sh A script to test for release (maintainer use only). safe-install.sh Safe install script from musl libc.
gen The bc math library, help texts, and code to generate C source. include All header files. locales Locale files, in .msg format. Patches welcome for translations. manuals Manuals for both programs. src All source code. tests All tests.