htole16, be16toh, le16toh, htobe32, htole32, be32toh,
le32toh, htobe64, htole64, be64toh, le64toh − convert
values between host and big-/little-endian byte order
_BSD_SOURCE /* See feature_test_macros(7) */
uint16_t htole16(uint16_t host_16bits);
uint16_t be16toh(uint16_t big_endian_16bits);
uint32_t htole32(uint32_t host_32bits);
uint32_t be32toh(uint32_t big_endian_32bits);
uint64_t htole64(uint64_t host_64bits);
uint64_t be64toh(uint64_t big_endian_64bits);
convert the byte encoding of integer values from the byte
order that the current CPU (the "host") uses, to
and from little-endian and big-endian byte order.
nn, in the name of each function indicates the size
of integer handled by the function, either 16, 32, or 64
with names of the form "htobenn" convert
from host byte order to big-endian order.
with names of the form "htolenn" convert
from host byte order to little-endian order.
with names of the form "benntoh" convert
from big-endian order to host byte order.
with names of the form "lenntoh" convert
from little-endian order to host byte order.
were added to glibc in version 2.9.
are nonstandard. Similar functions are present on the BSDs,
where the required header file is
<sys/endian.h> instead of
<endian.h>. Unfortunately, NetBSD, FreeBSD, and
glibc haven’t followed the original OpenBSD naming
convention for these functions, whereby the nn
component always appears at the end of the function name
(thus, for example, in NetBSD, FreeBSD, and glibc, the
equivalent of OpenBSDs "betoh32" is
are similar to the older byteorder(3) family of
functions. For example, be32toh() is identical to
of the byteorder(3) functions is that they are
standard functions available on all UNIX systems. On the
other hand, the fact that they were designed for use in the
context of TCP/IP means that they lack the 64-bit and
little-endian variants described in this page.
below display the results of converting an integer from host
byte order to both little-endian and big-endian byte order.
Since host byte order is either little-endian or big-endian,
only one of these conversions will have an effect. When we
run this program on a little-endian system such as x86-32,
we see the following:
x.u32 = 0x44332211
htole32(x.u32) = 0x44332211
htobe32(x.u32) = 0x11223344
main(int argc, char *argv)
x.arr = 0x11;
/* Lowest-address byte */
x.arr = 0x22;
x.arr = 0x33;
x.arr = 0x44;
/* Highest-address byte */
= 0x%x\n", x.u32);
printf("htole32(x.u32) = 0x%x\n", htole32(x.u32));
printf("htobe32(x.u32) = 0x%x\n",
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