permission denied

[CreatorB]

i think you compile g++and save in a media?
i should you to compile in /home/...
try it, i hope it work...

[modoran]

I hope you didn't try to chmod a.out on FAt32 or NTFS file system, do you ? Because it will not work that way.
Copy the file to your home directory, chmod 755 and try again (assuming your /home/username partition is mounted with execute permissions - usually it is)

And anyway g++ should make the file already executable for you (if you are in ext4 file system at least).

[ResidentBiscuit]

I believe it depends on your umask actually.