Networking: getaddrinfo using different ports

[kardon33]

My program sends commands to a different computer running a udp server.

My problem is that each different node is running on a different udp port and the code needs to take that into account by allowing the port to change depending on a int variable.

The to code snippets ive provided show what i got working and what i think should work but doesn't.

This Works.

 
   const char* po = "49240";
 
    if ((rv = getaddrinfo(lightIp, po, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
 
    }
 
 

This does not work.

 
 
     udpPort = 49240;
     const char* po = (char*)udpPort;
 
 
    if ((rv = getaddrinfo(lightIp, po, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
 
    }
 
 

[jkmyoung]

It looks like you're casting 49240 as a memory address. udpPort appears to be an integer, not a char*.

You might want:
udpPort = "49240";
const char* po = (char*) &udpPort;

[kardon33]

OK but how would you take an integer (udpPort) containing the number 49240 and set it to something that getaddrinfo could use? I got close with (const char* po = "49240"; ) but i haven't been able to get that to be dynamic using a variable.

Thanks for the help.

[jkmyoung]

Can you use the itoa function? http://www.cplusplus.com/reference/c.../cstdlib/itoa/

[kardon33]

I was finally able to get it working with the fallowing code:

   int udpPort = 12312;
   char buf[5];
   sprintf(buf,"%d",udpPort);
   po = (char*) &buf;
 
    if ((rv = getaddrinfo(lightIp, po, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
    }