[C/C#/C++] Portscanner

/* Name: Portscanner 
 * Author: Fallen Angel 
 * Usage: portscanner(.exe) [MODE] [IP] [RANGE] - [END]
 * Description: Scans the Ports of the IPAddr.
 * OS: Windows, Unix/Linux
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _WIN32
#include <windows.h>
#include <winsock.h>
#include <winsock2.h>
#define socket_t SOCKET
#else
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <unistd.h>
#define socket_t int
#endif

void cleanup(void);
int scanp(long port, char *host);
void printH(void);

struct sockaddr_in server;
struct hostent *host_info;

int main(int argc, char *argv[])
{
 int i;
 struct servent *s;
 #ifdef _WIN32
 WORD wVersionRequested;
 WSADATA wsaData;
 wVersionRequested = MAKEWORD (1, 1);
 
 atexit(cleanup);
 #endif

 if(argc != 5)
 {
 printH();
 exit(1);
 }
 
 #ifdef _WIN32
 if (WSAStartup (wVersionRequested, &wsaData) != 0)
 {
 printf("Failed to initialize Winsock\n");
 return 1;
 }
 #endif

 if(strcmp(argv[1],"-p") == 0 || strcmp(argv[1],"--port") == 0)
 { 
 printf("Scanning Portrange: "); 
 printf("(%s) %d - %d\n\n",argv[2], atoi(argv[3]), atol(argv[4]));
 
 for(i=atoi(argv[3]);i<atol(argv[4]);i++)
 { 
 if(scanp(i,argv[2]) != -1)
 {
 s = getservbyport(htons(i),"tcp"); 
 printf("Open Port: %d -> %s\n",i, (s == NULL) ? "Unknown" : s->s_name);
 continue;
 }
 }
 }
 else if(strcmp(argv[1],"-h") == 0 || strcmp(argv[1],"--help") == 0)
 {
 printH();
 }
 else
 {
 printH();
 } 

 return 0;
}

void cleanup(void)
{
 #ifdef _WIN32
 WSACleanup();
 #endif
}

int scanp(long port, char *host)
{
 unsigned long addr;
 socket_t sock;
 memset( &server, 0, sizeof (server));

 sock = socket(AF_INET, SOCK_STREAM, 0);
 if (sock < 0)
 {
 return(-1);
 }

 if ((addr = inet_addr( host )) != INADDR_NONE) {
 memcpy( (char *)&server.sin_addr, &addr, sizeof(addr));
 }
 else {
 host_info = gethostbyname( host );
 if (NULL == host_info)
 {
 return(-1);
 }
 memcpy( (char *)&server.sin_addr, host_info->h_addr,
 host_info->h_length);
 }
 server.sin_family = PF_INET;
 server.sin_port = htons( port );
 if (connect(sock, (struct sockaddr*)&server, sizeof( server)) < 0)
 {
 return(-1);
 }
 #ifdef _unix
 close(sock);
 #endif
 return 0;
}

void printH(void)
{
 printf("Mode:\n\t-h --help\tprints help\n\t-p --port" \
 "\tscans the port-range of the given ipaddr\n");
 printf("Example:\n\tPortscanner.exe -p 127.0.0.1 55 500\n");
}

void cleanup(void)
{
 #ifdef _WIN32
 WSACleanup();
 #endif
}

if(argc < 5 || argc > 5)