[Last Call] Learn how to a build a cloud-first strategyRegister Now

x
?
Solved

sorting arrays...

Posted on 2001-08-08
6
Medium Priority
?
217 Views
Last Modified: 2010-04-02
Hey all, I'm trying to find a quick way to sort an array.  This array has one element, a structure, and this structure has two elements.  Something like this:

struct MyStruct{
   int arg1;
   int arg2;
}MS;

struct MS MyArray[50];

Now I want to sort the array based on arg2.  Does anybody know a quick way of doing this.  I've thought about doing a bubble sort, but there has to be a quicker way.  I've tried using qsort, but I can't figure out how to make it look at arg2 as the sort key.

I need the code in C, not C++, and it must be ANSI compatable and able to run in DOS.  I'm using MS VC 1.52c for MSDOS programs.

Thanks.
0
Comment
Question by:Ra
  • 3
  • 2
6 Comments
 
LVL 30

Expert Comment

by:Axter
ID: 6365947
FYI,
You might want to post this type of question in the C topic area, or at least post a link to it.
http://www.experts-exchange.com/jsp/qList.jsp?ta=cprog
0
 
LVL 86

Accepted Solution

by:
jkr earned 400 total points
ID: 6365964

>>how to make it look at arg2 as the sort key

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

int compare( const void *arg1, const void *arg2 );

void main( int argc, char **argv )
{

struct MyStruct{
  int arg1;
  int arg2;
}MS;

struct MS MyArray[50];

//....

   qsort( (void *)MyArray, (size_t)50, sizeof( struct MS ), compare );

}

int compare( const void *arg1, const void *arg2 )
{
struct MS* p1 = (struct MS*) arg1;
struct MS* p1 = (struct MS*) arg1;

if ( p1->arg2 > p2->arg2) return ( 1);
if ( p1->arg2 < p2->arg2) return ( -1);
 
 
 return ( 0);
}
0
 

Author Comment

by:Ra
ID: 6366226
Axter, sorry, didn't realize there was a C topic area. ;)

jkr, thanks.  I'll test it when I get to work tomorrow morning.  I never thought about type casting those args to my structure.  It should work great.  I'll give you the points after I test it.
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 
LVL 86

Expert Comment

by:jkr
ID: 6366505
>>never thought about type casting

In good ol' "C", it's the only way :o)

In C++, using STL would be the idea...
0
 

Author Comment

by:Ra
ID: 6367938
Excellent, it works.  I had to change the second line in the compare function, a little copy and paste error there it looks like. ;)

Thanks jkr.
0
 
LVL 86

Expert Comment

by:jkr
ID: 6367957
>>a little copy and paste error there it looks like. ;)

Yup, I just saw it :o)
0

Featured Post

Important Lessons on Recovering from Petya

In their most recent webinar, Skyport Systems explores ways to isolate and protect critical databases to keep the core of your company safe from harm.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When writing generic code, using template meta-programming techniques, it is sometimes useful to know if a type is convertible to another type. A good example of when this might be is if you are writing diagnostic instrumentation for code to generat…
Article by: evilrix
Looking for a way to avoid searching through large data sets for data that doesn't exist? A Bloom Filter might be what you need. This data structure is a probabilistic filter that allows you to avoid unnecessary searches when you know the data defin…
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
The viewer will learn how to user default arguments when defining functions. This method of defining functions will be contrasted with the non-default-argument of defining functions.
Suggested Courses

834 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question