How do i check if a file is a regular file in C++?

DIR *dp;
struct dirent *dirp;

while ((dirp = readdir(dp)) != NULL) {
if ( isFile(dirp)) {
     cout << "IS A FILE!" << endl;
i++;
}

#include <boost/filesystem/path.hpp>
#include <boost/filesystem/operations.hpp>
#include <iostream>

int main() {
    using namespace boost::filesystem;

    path p("/bin/bash");
    if(is_regular_file(p)) {
        std::cout << "exists and is regular file" << std::endl;
    }
}

while ((dirp = readdir(dp)) != NULL) {
   if (!S_ISDIR(dirp->d_type)) {
        ...
        i++;
   }
}