.TH socket_getifidx 3 .SH NAME socket_getifidx \- get interface number .SH SYNTAX .B #include int \fBsocket_getifidx\fP(const char* \fIifname\fR); .SH DESCRIPTION socket_getifidx returns the interface number for a symbolic network interface name (like "eth0" on Linux, for example). The interface number can be used as scope_id for IPv6 communications on link-local addresses. If something goes wrong, socket_getifidx returns -1, setting errno appropriately. .SH "SEE ALSO" socket_getifname(3), socket_connect6(3)