a64l(3) — Linux manual page


A64L(3)                 Linux Programmer's Manual                A64L(3)

NAME         top

       a64l, l64a - convert between long and base-64

SYNOPSIS         top

       #include <stdlib.h>

       long a64l(const char *str64);
       char *l64a(long value);

   Feature Test Macro Requirements for glibc (see

       a64l(), l64a():
           _XOPEN_SOURCE >= 500
               || /* Glibc since 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _SVID_SOURCE

DESCRIPTION         top

       These functions provide a conversion between 32-bit long integers
       and little-endian base-64 ASCII strings (of length zero to six).
       If the string used as argument for a64l() has length greater than
       six, only the first six bytes are used.  If the type long has
       more than 32 bits, then l64a() uses only the low order 32 bits of
       value, and a64l() sign-extends its 32-bit result.

       The 64 digits in the base-64 system are:

              '.'  represents a 0
              '/'  represents a 1
              0-9  represent  2-11
              A-Z  represent 12-37
              a-z  represent 38-63

       So 123 = 59*64^0 + 1*64^1 = "v/".

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                 Attribute     Value               │
       │l64a()                    │ Thread safety │ MT-Unsafe race:l64a │
       │a64l()                    │ Thread safety │ MT-Safe             │

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008.

NOTES         top

       The value returned by l64a() may be a pointer to a static buffer,
       possibly overwritten by later calls.

       The behavior of l64a() is undefined when value is negative.  If
       value is zero, it returns an empty string.

       These functions are broken in glibc before 2.2.5 (puts most
       significant digit first).

       This is not the encoding used by uuencode(1).

SEE ALSO         top

       uuencode(1), strtoul(3)

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at

                               2021-03-22                        A64L(3)

Pages that refer to this page: strtoul(3)