be16toh, be32toh, be64toh, htobe16, htobe32, htobe64, htole16, htole32, htole64, le16toh, le32toh, le64toh — convert values between host and specified byte order
#include <endian.h>
uint16_t be16toh(uint16_t big_endian_16bits);
uint32_t be32toh(uint32_t big_endian_32bits);
uint64_t be64toh(uint64_t big_endian_64bits);
uint16_t htobe16(uint16_t host_16bits);
uint32_t htobe32(uint32_t host_32bits);
uint64_t htobe64(uint64_t host_64bits);
uint16_t htole16(uint16_t host_16bits);
uint32_t htole32(uint32_t host_32bits);
uint64_t htole64(uint64_t host_64bits);
uint16_t le16toh(uint16_t little_endian_16bits);
uint32_t le32toh(uint32_t little_endian_32bits);
uint64_t le64toh(uint64_t little_endian_64bits);
These functions shall convert integer values of various sizes between host representations and representations in a specified order.
On some implementations, these functions are defined as macros.
A little-endian representation of an integer has the least significant byte stored as the first byte, with the significance of the bytes increasing as the byte address increases. A big-endian representation has the most significant byte as the first byte, with the significance of the bytes reducing as the byte address increases.
- Note:
- Network byte order is big-endian.
For example, the uint32_t value 0x01020304 is represented as the four bytes 0x04, 0x03, 0x02, 0x01 on a little-endian host, and as 0x01, 0x02, 0x03, 0x04 on a big-endian host.
For each of the sizes 16, 32 and 64, the htobeSIZE() function shall convert from whatever order the host uses to big-endian representation, htoleSIZE() shall convert to little-endian representation, beSIZEtoh() shall convert from big-endian to host order, and leSIZEtoh() shall convert from little-endian to host order.
These functions shall return an unsigned integer of the appropriate size and representation.
No errors are defined.
#include <endian.h> #include <stdio.h> #include <stdlib.h>
int main(int argc, char *argv[]) { uint32_t val;
if (argc > 1) { val = (uint32_t)strtoul(argv[1], NULL, 0); printf("Value: %08x\n", val);
printf("As bytes:\n"); union { uint32_t asint; unsigned char asbytes[sizeof(uint32_t)]; } u; printf("Little endian: "); u.asint = htole32(val); for (int i = 0; i < sizeof(uint32_t); i++) { printf("%02x ", u.asbytes[i]); } printf("\n");
printf("Big endian : "); u.asint = htobe32(val); for (int i = 0; i < sizeof(uint32_t); i++) { printf("%02x ", u.asbytes[i]); } printf("\n"); } return 0; }
Since network order is defined as big-endian, the following functions are equivalent if <arpa/inet.h> is included:
<endian.h>
<arpa/inet.h>
htobe32
htonl
htobe16
htons
be32toh
ntohl
be16toh
ntohs
None.
None.
XBD <arpa/inet.h> , <endian.h>
First released in Issue 8.
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