Each case in a switch statement is, technically speaking, a label. For some obscure and old reasons, you are not allowed to have a variable declaration as the first line after a label. By commenting out the assignment

ptr = (struct sockaddr_in *) res->ai_addr;

the line

struct sockaddr_in *sockAddrIn = (struct sockaddr_in *) res->ai_addr;

becomes the first line after the label AF_INET: which, like I said, is illegal in C.

The solution is to wrap all of your case statements in curly brackets like so:

#include <stdio.h> #include <string.h> #include <stdlib.h> #include <netdb.h> #include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> int main (void) { struct addrinfo hints; memset (&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_DGRAM; hints.ai_flags = AI_CANONNAME; struct addrinfo *res; getaddrinfo ("example.com", "http", &hints, &res); printf ("Host: %s

", "example.com"); void *ptr; while (res != NULL) { printf("AI Family for current addrinfo: %i

", res->ai_family); switch (res->ai_family) { case AF_INET: { ptr = (struct sockaddr_in *) res->ai_addr; struct sockaddr_in *sockAddrIn = (struct sockaddr_in *) res->ai_addr; break; } } res = res->ai_next; } return 0; }

Anyway, I think this is better coding practice.