[Linux]計算目錄的大小

#include <"ftw.h">  
int Size;
int sum(const char *fpath, const struct stat *sb, int typeflag) {
    Size += sb->st_size;
    return 0;
}
void main()
{
  ftw("/tmp", &sum, 1);
  printf("the /tmp folder size:%d\n",Size);
  return;
}