Passing an array of structs

[DerPflug]

I have a program that reads an inventory binary file, loads the part_id and offset (via the "index_fill" function)into an array called "index", sorts "index", and should print the whole binary file with the complete record associated with each part_id. I get an error when passing the "index" array to my sort routine.

I have the following declarations at the beginning of the program:

#define MAX 50
int index_fill(index_t index[], FILE *INV);

//fills array
/*index_t is a struct consisting of the part_id and the offset*/

index_t index[MAX];

//array of index structs

index_t sort_index(index_t idx_file[], int rec_count);
index_t idx_file[MAX];

In the main function:
/*"source" is the file pointer to the source file;
"index_fill" function fills the array "index" and returns the number of records read from the file */

num_of_recs = index_fill(index, source);

//this works fine

sort_index(index, num_of_recs);

//error occurs here

the sort_index routine:

index_t 
sort_index(index_t idx_file[],int rec_count)
{
	int i;

//ID_LENGTH is 7, rec_count came from index_fill

	qsort(idx_file, rec_count, ID_LENGTH, compare);

//for testing only, print to verify order

	for(i = 0; i < rec_count; i++)
            printf( &quot;%s\n&quot;, idx_file[i]);

//ERRORS HERE

	return 0;
}

I have realized while writing this that the array of structs could be passed with pointers but I'm alittle pressed for time to get that working properly. When I get to the printf in sort_index I get an "unhandled error: access violation" error. I'm writing this in MS Visual C++.

Thanks in advance.

 

[rbobbitt]

It's hard to say for sure without seeing the complete code. In the future, try to post a complete, compilable code sample that demonstrates the problem.

However, how is ID_LENGTH derived? Whatever that value is, it should be equal to sizeof(index_t) when you pass it to qsort(). If that's not the problem, it would be interesting to see your compare routine.
Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts

 

[DerPflug]

Sorry, I thought it might be a bit much for this forum. But here it is nonetheless:

// Index_Test.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <stdlib.h> //for atoi
#include <stdio.h>
#include <string.h>
#include <conio.h> //for getch
#include <ctype.h> //for isalpha
#include <math.h>


#define MAX 50
#define ID_LENGTH 7

FILE *source,
	 *destination;

   typedef struct {
	int  month;
	int  day;
	int  year;
} date;

struct part_t {
	char  part_id[6+1];
	char  part_descr[20+1];
	double  unit_price;
	int  quan_onhand;
	int  reodr_pt;
	int reodr_qty;
	date reodr_date;
	int delete_flag;
};

struct index_t {
	char part_id[6 + 1];
	long recoffset;
};  //or }index[50] = {{&quot;\0&quot;, 0L}};

part_t partrecord;
void create_report(void);
int index_fill(index_t index[], FILE *INV);

//Functions
index_t index[MAX]; //array of index structs 
index_t sort_index(index_t idx_file[], int rec_count);
index_t idx_file[MAX];
int compare(const void *a, const void *b);

int main(int argc, char* argv[])
{
	FILE *inp, *outp; 

	char source_file[40],
		 dest_file[40];
	int num_of_recs;
	
	printf(&quot;\t\tThis will create a text file report from the inventory file.\n\n&quot;);
	printf(&quot;\t\tEnter the name of the source file with the .txt extension\n&quot;);
	printf(&quot;\t\tor type EXIT to leave > &quot;);
	scanf(&quot;%s&quot;, &source_file);
	fflush(stdin);
	while (strlen(source_file) > 40)
			{
				printf(&quot;\n\n\n\tThe filename you entered is too long.\n&quot;);
				printf(&quot;\tEnter it again with a max of 40 characters.&quot;);
				printf(&quot;\n\t> &quot;);
				scanf(&quot;%s&quot;, &source_file);
				fflush(stdin);
			}
			//add .txt extension if not there
	
	if (strcmp(source_file, &quot;EXIT&quot;) != 0)
	{
		while (!strstr(source_file, &quot;.txt&quot;))
		{
			strcat(source_file, &quot;.txt&quot;);
		}
		source = fopen(source_file, &quot;rb&quot;); //pointer that points to binary file
		if (source == NULL) //if there's an error go back to entry screen
		{
			printf(&quot;File Open Error&quot;);
			printf(&quot;\n\nThis file either does not exist or&quot;);
			printf(&quot; it was entered incorrectly.\n\n&quot;);
			//exit(EXIT_FAILURE);
		}
	}
	
   if (strcmp(source_file, &quot;EXIT&quot;) != 0)
   {  //main if begin
	 printf(&quot;\n\n&quot;);
	 printf(&quot;\t\tEnter the name of the destination file with the .dat\n&quot;);
	 printf(&quot;\t\textension or type EXIT to leave > &quot;);
	 scanf(&quot;%s&quot;, &dest_file);
	 fflush(stdin);
	 while (strlen(dest_file) > 40)
			{
				printf(&quot;\n\n\n\tThe filename you entered is too long.\n&quot;);
				printf(&quot;\tEnter it again with a max of 40 characters.&quot;);
				printf(&quot;\n\t> &quot;);
				scanf(&quot;%s&quot;, &dest_file);
				fflush(stdin);
			}
			//add .dat extension if not there
	 if (strcmp(dest_file, &quot;EXIT&quot;) != 0)
	 {
		 while (!strstr(dest_file, &quot;.dat&quot;))
		{
			strcat(dest_file, &quot;.dat&quot;);
		}

		destination = fopen(dest_file, &quot;w&quot;); //pointer that points to binary file
		if (destination == NULL) //if there's an error go back to entry screen
		{
			printf(&quot;File Open Error&quot;);
			printf(&quot;\n\nThis file either does not exist or&quot;);
			printf(&quot; it was entered incorrectly.\n\n&quot;);
			//exit(EXIT_FAILURE);
		}
	 }
   } //main if end
	//j = 0;
	if (strcmp(source_file, &quot;EXIT&quot;) != 0 && strcmp(dest_file, &quot;EXIT&quot;) != 0)
	{  	
		//index_fill(index, source);
		num_of_recs = index_fill(index, source);
		sort_index(index, num_of_recs);
		
		printf(&quot;You made it here.&quot;);
		system(&quot;cls&quot;);
	}
	
    fclose(source);
	return 0;
}

	/*
void
create_report(void)//char source[40], char destination[40])
{
	/*****************************************************************
	*This function reads the binary file and creates a text report file.
	*****************************************************************/
	
	
//}
int 
index_fill(index_t index[], FILE *INV) //array of index structs and pointer to filename
{
	//file should already be open at this point
	//open file once during program and leave open until end
	int REC_COUNT = 0,z;
	long recoffset;
	part_t partrec;
	rewind(INV);  //goes to top of file

	/*Now set recoffset to current pointer position */
	recoffset = ftell(INV); 
	fread(&partrec, sizeof(part_t), 1, INV); //initial read
	while(!feof(INV))
	{
		index[REC_COUNT].recoffset = recoffset;
		strcpy(index[REC_COUNT++].part_id, partrec.part_id);
		recoffset = ftell(INV);
		fread(&partrec, sizeof(part_t),1,INV);
	} //end while
	//code for sort on part id
	for(z=0; z < REC_COUNT; z++)
	{
		printf(&quot;\n%s  %d&quot;, index[z].part_id, index[z].recoffset);
	}
	return REC_COUNT;
}

index_t 
sort_index(index_t idx_file[],int rec_count)
{
	int i;

	qsort(idx_file, rec_count, ID_LENGTH, compare);
	for(i = 0; i < rec_count; i++)
      printf( &quot;%s\n&quot;, idx_file[i]);

	return idx_file[rec_count];
}

int
compare(const void *a, const void *b)
{
	return(strcmp((char *)a,(char *)b));
}

 

[rbobbitt]

Didn't you get what I said about ID_LENGTH? You define it as 7, but it should actually be sizeof(index_t). I didn't look at the rest of your code, so that may not be the only problem.

BTW, even though it is written in a sort of C style, it uses C++-specific constructs (such as using index_t instead as struct index_t). I imagine that your compiler must be treating it as C++ as well, given the file name you're using. Is that what you want?
Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts

 

[DerPflug]

It appears that isn't my only problem. I've been sending the entire struct to qsort, so it's probably confused as to how to sort it. I only need the part_id portion sorted. Yes, since we're running MS Visual C++ the C++ constructs are fine.