c++ extern c

c++ extern c

#include    <cstdlib>
#include    <fstream>
#include    <iomanip>   
#include    <iostream>  

extern "C" {
#include <sys/time.h>
#include <unistd.h>
}
using namespace std;

// ===  FUNCTION  ======================================================================
//         Name:  main
//  Description:  main function
// =====================================================================================
    int
main ( int argc, char *argv[] )
{
    int i = 0, j = 0;
    struct timeval tv1, tv2;
    double sec = 0;
    gettimeofday(&tv1, 0); 
    for(i = 0; i < 1000000000 ; i++)
    {
        j++;
    }
    cout    << j << endl;
    gettimeofday(&tv2, 0);
    sec = (double)(tv2.tv_sec - tv1.tv_sec) +  (double)(tv2.tv_usec - tv1.tv_usec) / 1000000;
    printf("time1: %f\n", sec);
    cout << sec <<endl;
    return EXIT_SUCCESS;
}        // ----------  end of function main  ----------