#include "unp.h" #include int main(int argc, char **argv) { int i, sockfd, numif; char buf[1024]; sockfd = Socket(AF_INET, SOCK_DGRAM, 0); numif = 999; Ioctl(sockfd, SIOCGIFNUM, &numif); printf("numif = %d\n", numif); i = ioctl(sockfd, SIOCGHIWAT, &buf); printf("i = %d, errno = %d\n", i, errno); exit(0); }