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Full Discussion: relative pointers on Unix
Top Forums Programming relative pointers on Unix Post 77336 by jim mcnamara on Thursday 7th of July 2005 10:16:26 AM
Old 07-07-2005
Microsoft is bad about C standards conformance.

This is a relative pointer, a pointer that is set to a base value and then offset by a fixed "distance"
Code:
int foo()
{
    int a[100]={0};     
    int *base=a;          
    int i=0;              
    for(i=0;i<100;i++)    
    {                     
         int q=*(base+i);   /* base+i is the relative pointer */
         printf("%d\n",q);
    }                     
    return 0;
}

This is also a relative pointer:
Code:
     int foo( int *a)
     {
           int i=0;
           for(i=0;i<100;i++)
           {
               printf("%d\n", a[i]); /* a[i] is also a relative pointer */
           }
           return 0;
      }

The a[i] thing is array notation, but it is an offset against a base. They are all compiled into the same machine code.
 

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Filename(3)							   OCaml library						       Filename(3)

NAME
Filename - Operations on file names. Module Module Filename Documentation Module Filename : sig end Operations on file names. val current_dir_name : string The conventional name for the current directory (e.g. . in Unix). val parent_dir_name : string The conventional name for the parent of the current directory (e.g. .. in Unix). val dir_sep : string The directory separator (e.g. / in Unix). Since 3.11.2 val concat : string -> string -> string concat dir file returns a file name that designates file file in directory dir . val is_relative : string -> bool Return true if the file name is relative to the current directory, false if it is absolute (i.e. in Unix, starts with / ). val is_implicit : string -> bool Return true if the file name is relative and does not start with an explicit reference to the current directory ( ./ or ../ in Unix), false if it starts with an explicit reference to the root directory or the current directory. val check_suffix : string -> string -> bool check_suffix name suff returns true if the filename name ends with the suffix suff . val chop_suffix : string -> string -> string chop_suffix name suff removes the suffix suff from the filename name . The behavior is undefined if name does not end with the suffix suff . val chop_extension : string -> string Return the given file name without its extension. The extension is the shortest suffix starting with a period and not including a directory separator, .xyz for instance. Raise Invalid_argument if the given name does not contain an extension. val basename : string -> string Split a file name into directory name / base file name. If name is a valid file name, then concat (dirname name) (basename name) returns a file name which is equivalent to name . Moreover, after setting the current directory to dirname name (with Sys.chdir ), references to basename name (which is a relative file name) designate the same file as name before the call to Sys.chdir . This function conforms to the specification of POSIX.1-2008 for the basename utility. val dirname : string -> string See Filename.basename . This function conforms to the specification of POSIX.1-2008 for the dirname utility. val temp_file : ?temp_dir:string -> string -> string -> string temp_file prefix suffix returns the name of a fresh temporary file in the temporary directory. The base name of the temporary file is formed by concatenating prefix , then a suitably chosen integer number, then suffix . The optional argument temp_dir indicates the tempo- rary directory to use, defaulting to the current result of Filename.get_temp_dir_name . The temporary file is created empty, with permis- sions 0o600 (readable and writable only by the file owner). The file is guaranteed to be different from any other file that existed when temp_file was called. Raise Sys_error if the file could not be created. Before3.11.2 no ?temp_dir optional argument val open_temp_file : ?mode:Pervasives.open_flag list -> ?temp_dir:string -> string -> string -> string * Pervasives.out_channel Same as Filename.temp_file , but returns both the name of a fresh temporary file, and an output channel opened (atomically) on this file. This function is more secure than temp_file : there is no risk that the temporary file will be modified (e.g. replaced by a symbolic link) before the program opens it. The optional argument mode is a list of additional flags to control the opening of the file. It can contain one or several of Open_append , Open_binary , and Open_text . The default is [Open_text] (open in text mode). Raise Sys_error if the file could not be opened. Before3.11.2 no ?temp_dir optional argument val get_temp_dir_name : unit -> string The name of the temporary directory: Under Unix, the value of the TMPDIR environment variable, or "/tmp" if the variable is not set. Under Windows, the value of the TEMP environment variable, or "." if the variable is not set. The temporary directory can be changed with File- name.set_temp_dir_name . Since 4.00.0 val set_temp_dir_name : string -> unit Change the temporary directory returned by Filename.get_temp_dir_name and used by Filename.temp_file and Filename.open_temp_file . Since 4.00.0 val temp_dir_name : string Deprecated. The name of the initial temporary directory: Under Unix, the value of the TMPDIR environment variable, or "/tmp" if the vari- able is not set. Under Windows, the value of the TEMP environment variable, or "." if the variable is not set. This function is depre- cated; Filename.get_temp_dir_name should be used instead. Since 3.09.1 val quote : string -> string Return a quoted version of a file name, suitable for use as one argument in a command line, escaping all meta-characters. Warning: under Windows, the output is only suitable for use with programs that follow the standard Windows quoting conventions. OCamldoc 2014-06-09 Filename(3)
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