word count c++

wcpp.cpp

#include <algorithm>
#include <fcntl.h>
#include <iostream>
#include <string.h>
#include <unistd.h>
using namespace std;

constexpr int BUFFER_SIZE = 1024 * 1024;

size_t line_count(const char *filename) {
  int fd = open(filename, O_RDONLY);
  if (fd == -1) {
    cout << filename << ": " << strerror(errno) << endl;
    return -1;
  }
  posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
  char buf[BUFFER_SIZE + 1];
  size_t lines = 0;
  while (ssize_t rb = read(fd, buf, BUFFER_SIZE)) {
    if (rb == -1) {
      cout << filename << ": " << strerror(errno) << endl;
      close(fd);
      return 0;
    }
    if (!rb) {
      break;
    }
    // lines += std::count(buf, buf+rb, '\n');

    for (char *p = buf; (p = (char *)memchr(p, '\n', (buf + rb) - p)); p++)
      lines++;
  }
  close(fd);

  return lines;
}

int main(int argc, char const *argv[]) {
  // ios_base::sync_with_stdio(0);
  for (int i = 1; i < argc; i++) {
    cout << "  " << line_count(argv[i]) << " " << argv[i] << "\n";
  }
  return 0;
}