A64L(3) Library Functions Manual A64L(3)

a64l, l64a — convert between 32-bit integer and radix-64 ASCII string

#include <stdlib.h>

long
a64l(const char *s);

char *
l64a(long value);

The () and l64a() 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 a radix-64 notation.

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

The () function takes a pointer to a null-terminated radix-64 representation and returns a corresponding 32-bit value. If the string pointed to by s contains more than six characters, a64l() will use the first six. a64l() scans the character string from left to right, decoding each character as a 6-bit radix-64 number. If a long integer is larger than 32 bits, the return value will be sign-extended.

() takes a long integer argument value and returns a pointer to the corresponding radix-64 representation.

On success, a64l() returns a 32-bit representation of s. If s is a null pointer or if it contains digits other than those described above. a64l() returns -1 and sets the global variable errno to EINVAL.

On success, l64a() returns a pointer to a string containing the radix-64 representation of value. If value is 0, l64a() returns a pointer to the empty string. If value is negative, l64a() returns a null pointer and sets the global variable errno to EINVAL.

The value returned by () is a pointer into a static buffer, the contents of which will be overwritten by subsequent calls.

The value returned by () may be incorrect if the value is too large; for that reason, only strings that resulted from a call to l64a() should be used to call a64l().

If a long integer is larger than 32 bits, only the low-order 32 bits are used.

The a64l() and l64a() functions conform to X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”).

August 17, 1997 macOS 15.2