inet_ntop(3) Library Functions Manual inet_ntop(3)

inet_ntop - convert IPv4 and IPv6 addresses from binary to text form

Standard C library (libc, -lc)

#include <arpa/inet.h>
const char *inet_ntop(int af, const void *restrict src,
                      char dst[restrict .size], socklen_t size);

This function converts the network address structure src in the af address family into a character string. The resulting string is copied to the buffer pointed to by dst, which must be a non-null pointer. The caller specifies the number of bytes available in this buffer in the argument size.

inet_ntop() extends the inet_ntoa(3) function to support multiple address families, inet_ntoa(3) is now considered to be deprecated in favor of inet_ntop(). The following address families are currently supported:

src points to a struct in_addr (in network byte order) which is converted to an IPv4 network address in the dotted-decimal format, "ddd.ddd.ddd.ddd". The buffer dst must be at least INET_ADDRSTRLEN bytes long.
src points to a struct in6_addr (in network byte order) which is converted to a representation of this address in the most appropriate IPv6 network address format for this address. The buffer dst must be at least INET6_ADDRSTRLEN bytes long.

On success, inet_ntop() returns a non-null pointer to dst. NULL is returned if there was an error, with errno set to indicate the error.

af was not a valid address family.
The converted address string would exceed the size given by size.

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
inet_ntop () Thread safety MT-Safe locale



Note that RFC 2553 defines a prototype where the last argument size is of type size_t. Many systems follow RFC 2553. glibc 2.0 and 2.1 have size_t, but 2.2 and later have socklen_t.

AF_INET6 converts IPv4-mapped IPv6 addresses into an IPv6 format.

See inet_pton(3).

getnameinfo(3), inet(3), inet_pton(3)

2024-05-02 Linux man-pages 6.9.1