.TH socket_mcjoin4 3 .SH NAME socket_mcjoin4 \- join a multicast group .SH SYNTAX .B #include int \fBsocket_mcjoin4\fP(int \fIs\fR,const char \fIgroupip\fR[4],const char \fIinterface\fR[4]); .SH DESCRIPTION socket_mcjoin4 joins the IPv4 multicast group \fIgroupip\fR on \fIinterface\fR. If something goes wrong, socket_mcjoin4 returns -1, setting errno appropriately. .SH "SEE ALSO" socket_mcleave4(3), socket_mcjoin6(3), socket_getifidx(3)