pcap_init(3PCAP) man page

#include <pcap/pcap.h>

char errbuf[PCAP_ERRBUF_SIZE];

int pcap_init(unsigned int opts, char *errbuf);

PCAP_MMAP_32BIT

Map packet buffers with 32-bit addresses.

PCAP_CHAR_ENC_LOCAL

Treat all strings supplied as arguments, and return all strings to the caller, as being in the local character encoding.

PCAP_CHAR_ENC_UTF_8

Treat all strings supplied as arguments, and return all strings to the caller, as being in UTF-8.

On UNIX-like systems, the local character encoding is assumed to be UTF-8, so no character encoding transformations are done.

On Windows, the local character encoding is the local ANSI code page.

If pcap_init() is not called, strings are treated as being in the local ANSI code page on Windows, pcap_lookupdev(3PCAP) will succeed if there is a device on which to capture, and pcap_create(3PCAP) makes an attempt to check whether the string passed as an argument is a UTF-16LE string - note that this attempt is unsafe, as it may run past the end of the string - to handle pcap_lookupdev() returning a UTF-16LE string. Programs that don't call pcap_init() should, on Windows, call pcap_wsockinit() to initialize Winsock; this is not necessary if pcap_init() is called, as pcap_init() will initialize Winsock itself on Windows.