A64L(3) FreeBSD Library Functions Manual A64L(3)


a64l, l64a, l64a_rconvert between a long integer and a base-64 ASCII string


Standard C Library (libc, -lc)


#include < stdlib.h>

a64l( const char *s);

char *
l64a( long int l);

l64a_r( long int l, char *buffer, int buflen);


These functions are used to maintain numbers stored in radix-64 ASCII characters. This is a notation by which 32-bit integers can be represented by up to six characters; each character represents a digit in radix-64 notation. If the type long contains more than 32 bits, only the low-order 32 bits are used for these operations.

The characters used to represent “digits” are ‘ .’ for 0, ‘ /’ for 1, ‘ 0’ - ‘ 9’ for 2 - 11, ‘ A’ - ‘ Z’ for 12 - 37, and ‘ a’ - ‘ z’ for 38 - 63.

The a64l() function takes a pointer to a radix-64 representation, in which the first digit is the least significant, and returns a corresponding long value. If the string pointed to by s contains more than six characters, a64l() uses the first six. If the first six characters of the string contain a null terminator, a64l() uses only characters preceding the null terminator. The a64l() function scans the character string from left to right with the least significant digit on the left, decoding each character as a 6-bit radix-64 number. If the type long contains more than 32 bits, the resulting value is sign-extended. The behavior of a64l() is unspecified if s is a null pointer or the string pointed to by s was not generated by a previous call to l64a().

The l64a() function takes a long argument and returns a pointer to the corresponding radix-64 representation. The behavior of l64a() is unspecified if value is negative.

The value returned by l64a() is a pointer into a static buffer. Subsequent calls to l64a() may overwrite the buffer.

The l64a_r() function performs a conversion identical to that of l64a() and stores the resulting representation in the memory area pointed to by buffer, consuming at most buflen characters including the terminating NUL character.


On successful completion, a64l() returns the long value resulting from conversion of the input string. If a string pointed to by s is an empty string, a64l() returns 0.

The l64a() function returns a pointer to the radix-64 representation. If value is 0, l64a() returns a pointer to an empty string.




The a64l(), l64a(), and l64a_r() functions are derived from NetBSD with modifications. They appeared in FreeBSD 6.1.


The a64l(), l64a(), and l64a_r() functions were added to FreeBSD by Tom Rhodes <trhodes@FreeBSD.org>. Almost all of this manual page came from the POSIX standard.
November 20, 2005 FreeBSD