pcap抓取数据包并储存到.txt中

#include <string>
#include <iostream>
#include <pcap.h>
 
using namespace std;
 
int main(int argc, char *argv[])
{
    /*
    * Step 2 - Get a file name
    */
 
    string file = "C:\\users\\jared\\testfiles\\smallcapture.pcap";
 
    /*
    * Step 3 - Create an char array to hold the error.
    */
 
    // Note: errbuf in pcap_open functions is assumed to be able to hold at least PCAP_ERRBUF_SIZE chars
    //       PCAP_ERRBUF_SIZE is defined as 256.
    // http://www.winpcap.org/docs/docs_40_2/html/group__wpcap__def.html
    char errbuff[PCAP_ERRBUF_SIZE];
 
    /*
    * Step 4 - Open the file and store result in pointer to pcap_t
    */
 
    // Use pcap_open_offline
    // http://www.winpcap.org/docs/docs_41b5/html/group__wpcapfunc.html#g91078168a13de8848df2b7b83d1f5b69
    pcap_t * pcap = pcap_open_offline(file.c_str(), errbuff);
 
    /*
    * Step 5 - Create a header and a data object
    */
 
    // Create a header object:
    // http://www.winpcap.org/docs/docs_40_2/html/structpcap__pkthdr.html
    struct pcap_pkthdr *header;
 
    // Create a character array using a u_char
    // u_char is defined here:
    // C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Include\WinSock2.h
    // typedef unsigned char   u_char;
    const u_char *data;
 
    /*
    * Step 6 - Loop through packets and print them to screen
    */
    u_int packetCount = 0;
    while (int returnValue = pcap_next_ex(pcap, &header, &data) >= 0)
    {
        // Print using printf. See printf reference:
        // http://www.cplusplus.com/reference/clibrary/cstdio/printf/
 
        // Show the packet number
        printf("Packet # %i\n", ++packetCount);
 
        // Show the size in bytes of the packet
        printf("Packet size: %d bytes\n", header->len);
 
        // Show a warning if the length captured is different
        if (header->len != header->caplen)
            printf("Warning! Capture size different than packet size: %ld bytes\n", header->len);
 
        // Show Epoch Time
        printf("Epoch Time: %d:%d seconds\n", header->ts.tv_sec, header->ts.tv_usec);
 
        // loop through the packet and print it as hexidecimal representations of octets
        // We also have a function that does this similarly below: PrintData()
        for (u_int i=0; (i < header->caplen ) ; i++)
        {
            // Start printing on the next after every 16 octets
            if ( (i % 16) == 0) printf("\n");
 
            // Print each octet as hex (x), make sure there is always two characters (.2).
            printf("%.2x ", data[i]);
        }
 
        // Add two lines between packets
        printf("\n\n");
    }
}