Why is C/C++ considered low-level languages??? Post: 302622079

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Top Forums Programming Why is C/C++ considered low-level languages??? Post 302622079 by Corona688 on Wednesday 11th of April 2012 01:35:46 PM

04-11-2012

Registered User

C/C++ are considered high/low level languages because you can write fairly high-level code, with complicated data structures and local variables and functions and various other things you'd find in "high"-level languages, and still have it translated into 100% pure uninterpreted assembly language. You can even write freestanding things like bootloaders and operating systems in C/C++ because you can exercise fine control over what external things are needed -- or, more to the point, aren't needed. You can forgo the standard libraries entirely and write code that depends on absolutely nothing.

This is very different from Java where everything has to be fed through an interpreter all the time. It's not the computer's native tongue, so to speak. You couldn't write a bootloader in it -- you'd need something else to load java first. It's not freestanding, not independent.

Your question unfortunately sounds a bit naive. Writing a disk defragmenter isn't trivial -- you need to understand a lot more than the language, you need to understand the structures of the filesystem in question. If you don't know enough about a filesystem to know which sectors to grab to find out what information, you can't write a defragmenter.

They're often written in C/C++, yes. They don't have to be, but because the structures for these filesystems are C/C++ anyway, it may be easiest to use them rather than reinvent the wheel.

If you want to build a defragmenter for educational reasons, I'd suggest working on the MS-DOS FAT16 filesystem which has very simple organization, then working up from there.

Last edited by Corona688; 04-11-2012 at 02:42 PM..

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LEARN ABOUT OSF1

xfs_freeze

xfs_freeze(8)						      System Manager's Manual						     xfs_freeze(8)

NAME

       xfs_freeze - suspend access to an XFS filesystem

SYNOPSIS

       xfs_freeze -f | -u mount-point

DESCRIPTION

       xfs_freeze suspends and resumes access to an XFS filesystem (see xfs(5)).

       xfs_freeze  halts  new access to the filesystem and creates a stable image on disk.  xfs_freeze is intended to be used with volume managers
       and hardware RAID devices that support the creation of snapshots.

       The mount-point argument is the pathname of the directory where the filesystem is mounted.  The filesystem must be  mounted  to	be  frozen
       (see mount(8)).

       The  -f flag requests the specified XFS filesystem to be frozen from new modifications.	When this is selected, all ongoing transactions in
       the filesystem are allowed to complete, new write system calls are halted, other calls which modify the	filesystem  are  halted,  and  all
       dirty data, metadata, and log information are written to disk.  Any process attempting to write to the frozen filesystem will block waiting
       for the filesystem to be unfrozen.

       Note that even after freezing, the on-disk filesystem can contain information on files that are still in the process of	unlinking.   These
       files will not be unlinked until the filesystem is unfrozen or a clean mount of the snapshot is complete.

       The  -u	flag  is used to un-freeze the filesystem and allow operations to continue.  Any filesystem modifications that were blocked by the
       freeze are unblocked and allowed to complete.

       One of -f or -u must be supplied to xfs_freeze.

NOTES

       A copy of a frozen XFS filesystem will usually have the same universally unique identifier (UUID) as the original, and  thus  may  be  pre-
       vented from being mounted.  The XFS nouuid mount option can be used to circumvent this issue.

       In  Linux  kernel version 2.6.29, the interface which XFS uses to freeze and unfreeze was elevated to the VFS, so that this tool can now be
       used on many other Linux filesystems.

SEE ALSO

       xfs(5), lvm(8), mount(8).

																     xfs_freeze(8)