troubleshooting Question

Passing arguments to main function in C++

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newpro2010 asked on
CC++Visual C++.NET
12 Comments1 Solution931 ViewsLast Modified:

I have my own application and I need to insert this code in a saparate class and call it from my own main function.
The problem that I am facing is when I change this main function into another and try to call it from my main function I get a bunch of error messages, mainly becuase of the argument passing (I think)

Any suggestions?
#include "stdafx.h"
#include "pcap.h"

/* prototype of the packet handler */
void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data);

int main(int argc, char **argv)
pcap_if_t *alldevs;
pcap_if_t *d;
int inum;
int i=0;
pcap_t *adhandle;
char errbuf[PCAP_ERRBUF_SIZE];
pcap_dumper_t *dumpfile;

struct pcap_pkthdr *header;
const u_char *pkt_data;
int res;
pcap_t *fp;
    /* Check command line */
    if(argc != 2)
        printf("usage: %s filename", argv[0]);
        return -1;
    /* Retrieve the device list on the local machine */
    if (pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) == -1)
        fprintf(stderr,"Error in pcap_findalldevs: %s\n", errbuf);
    /* Print the list */
    for(d=alldevs; d; d=d->next)
        printf("%d. %s", ++i, d->name);
        if (d->description)
            printf(" (%s)\n", d->description);
            printf(" (No description available)\n");

        printf("\nNo interfaces found! Make sure WinPcap is installed.\n");
        return -1;
    printf("Enter the interface number (1-%d):",i);
    scanf_s("%d", &inum);
    if(inum < 1 || inum > i)
        printf("\nInterface number out of range.\n");
        /* Free the device list */

		return -1;
    /* Jump to the selected adapter */
    for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);
    /* Open the device */
    if ( (adhandle= pcap_open(d->name,          // name of the device
                              65536,            // portion of the packet to capture
                                                // 65536 guarantees that the whole packet will be captured on all the link layers
                              PCAP_OPENFLAG_PROMISCUOUS,    // promiscuous mode
                              1000,             // read timeout
                              NULL,             // authentication on the remote machine
                              errbuf            // error buffer
                              ) ) == NULL)
        fprintf(stderr,"\nUnable to open the adapter. %s is not supported by WinPcap\n", d->name);
        /* Free the device list */
        return -1;

    /* Open the dump file */
    dumpfile = pcap_dump_open(adhandle, argv[1] ); //adhandle, argv[1]

        fprintf(stderr,"\nError opening output file\n");
        return -1;
    printf("\nlistening on %s... Press Ctrl+C to stop...\n", d->description);
    /* At this point, we no longer need the device list. Free it */
    /* start the capture */
    pcap_loop(adhandle, 0, packet_handler, (unsigned char *)dumpfile);

    /* while((res = pcap_next_ex( fp, &header, &pkt_data)) >= 0)
	pcap_dump((unsigned char *) dumpfile, header, pkt_data);
    return 0;

// Callback function invoked by libpcap for every incoming packet 
void packet_handler(u_char *dumpfile, const struct pcap_pkthdr *header, const u_char *pkt_data)
    // save the packet on the dump file 
    pcap_dump(dumpfile, header, pkt_data);
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