Creating local variables in a program?

fl0at · 01-02-2008, 04:01 PM

Hello,

I want to make a program which reads a file to make multiple automated tasks.
This file is used to CREATE local variables in a program (like the "INT var =" in C, the "set VAR=" in DOS BATCH, the "VAR=" in SH, etc.). This means the variables name can vary.

For example (commentary character is #) :

Code:

################################################
############## PRINCIPAL SETTINGS ##############
################################################
 
FILEKEY = keylist.cfg
USER_0 = Lincoln
USER_1 = Kennedy
NUMBER_X = 82
NUMBER_Y = 139
NUMBER_Z = 226
INTERVAL = 927

[...]

My question is : How can I do this? I mean, how can I allocate memory to create local variables used in the program for various tasks?

If possible, I would like to not use the shell environment i.e. no calls of getenv() or system().
Also, would it be possible that the names of the variables in the program would be the same that in the file?

Thank you!

Sincerely,

fl0at

Elysia · 01-02-2008, 04:13 PM

Sure, if you use a map. But that's not exactly an easy thing to design (and the CRT doesn't have any such thing), so the best thing to do would be switch to C++ and use std::map. Otherwise, design your own map or crawl the web for one.
Basically, you can combine a key/pair. A key points to a specific variable which can set or lookup. You can look at the tutorial for std::map for more information.

fl0at · 01-04-2008, 06:39 PM

Hi,

First, thank you Elysia for taking the time to answer me clearly.

After reading your post, I tried to *almost* "crawl the web" to find documentation about maps. The only problem is that the word "map" has several meaning, so, even if i google programming subjects about "maps", I can't find what I am searching for.

I was wondering if anyone could explicate me what is a map, or if anyone could point me to a decent documentation.
I do not project to use a map from someone else than me, but I would like to understand what is the principle of a map.
I am sure I can code one myself :-]

Unfortunately, for the moment, I am concentrated on C, and I don't know well C++ :-[

Thank you,

Sincerely,

fl0at

robwhit · 01-04-2008, 06:44 PM

http://www.google.com/search?q=map+STL

tabstop · 01-04-2008, 06:45 PM

The more generic term is "associative array". Wikipedia has a short article, and there are others out there as well. (You'll probably get a lot of perl matches, since it's a built-in data type in that language.) You can search on the full C++ name "std::map" as well.

cpjust · 01-04-2008, 07:34 PM

std::map is a C++ container.
Since you're using C, you'll have to reinvent the wheel the hard way.

For your purposes, a linked list of structs like this might be appropriate:

Code:

enum var_type
{
    INT,
    STRING,
    DOUBLE
}

struct Variable
{
    var_type  varType;
    char*  varName;
    void*  varData;
};

01-02-2008, 04:01 PM	#1
fl0at Registered User Join Date: Jan 2008 Location: On the Earth. Posts: 2	Creating local variables in a program? Hello, I want to make a program which reads a file to make multiple automated tasks. This file is used to CREATE local variables in a program (like the "INT var =" in C, the "set VAR=" in DOS BATCH, the "VAR=" in SH, etc.). This means the variables name can vary. For example (commentary character is #) : Code: ################################################ ############## PRINCIPAL SETTINGS ############## ################################################ FILEKEY = keylist.cfg USER_0 = Lincoln USER_1 = Kennedy NUMBER_X = 82 NUMBER_Y = 139 NUMBER_Z = 226 INTERVAL = 927 [...] My question is : How can I do this? I mean, how can I allocate memory to create local variables used in the program for various tasks? If possible, I would like to not use the shell environment i.e. no calls of getenv() or system(). Also, would it be possible that the names of the variables in the program would be the same that in the file? Thank you! Sincerely, fl0at
fl0at is offline

01-04-2008, 06:39 PM	#3
fl0at Registered User Join Date: Jan 2008 Location: On the Earth. Posts: 2	Hi, First, thank you Elysia for taking the time to answer me clearly. After reading your post, I tried to almost "crawl the web" to find documentation about maps. The only problem is that the word "map" has several meaning, so, even if i google programming subjects about "maps", I can't find what I am searching for. I was wondering if anyone could explicate me what is a map, or if anyone could point me to a decent documentation. I do not project to use a map from someone else than me, but I would like to understand what is the principle of a map. I am sure I can code one myself :-] Unfortunately, for the moment, I am concentrated on C, and I don't know well C++ :-[ Thank you, Sincerely, fl0at
fl0at is offline

01-04-2008, 06:44 PM	#4
robwhit Registered User Join Date: Oct 2001 Posts: 2,110	http://www.google.com/search?q=map+STL
robwhit is offline

01-04-2008, 06:45 PM	#5
tabstop and the Hat of Guessing Join Date: Nov 2007 Posts: 8,825	The more generic term is "associative array". Wikipedia has a short article, and there are others out there as well. (You'll probably get a lot of perl matches, since it's a built-in data type in that language.) You can search on the full C++ name "std::map" as well.
tabstop is online now

01-04-2008, 07:34 PM	#6
cpjust and the hat of sweating Join Date: Aug 2007 Location: Toronto, ON Posts: 3,282	std::map is a C++ container. Since you're using C, you'll have to reinvent the wheel the hard way. For your purposes, a linked list of structs like this might be appropriate: Code: enum var_type { INT, STRING, DOUBLE } struct Variable { var_type varType; char* varName; void* varData; };
cpjust is online now

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