Parsing a csv file in C

[matt nagel]

Hi there, I am fairly new to programming and trying create a program to parse csv data into an array. I have been following an example I found on this site but I am running into a segmentation fault (even if I copy code directly). I am fairly sure the problem lies in the while loop, I just cant see it.

****Sample Csv Data****
1.0235, 2.1112, 1.9972
3.0139, 1.1876, 2.91785
1.9295, 2.1322, 2.4821

I realize its probably overkill for my purpose so if anyone could point me to a simpler solution that would be appreciated too.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXFLDS 200     /* maximum possible number of fields */
#define MAXFLDSIZE 32   /* longest possible field + 1 = 31 byte field */

void parse( char *record, char *delim, char arr[][MAXFLDSIZE],int *fldcnt)
{
    char*p=strtok(record,delim);
    int fld=0;
    
    while(*p)
    {
        strcpy(arr[fld],p);
		fld++;
		p=strtok('\0',delim);
	}		
	*fldcnt=fld;
}

int main(int argc, char *argv[])
{
	char tmp[1024]={0x0};
	int fldcnt=0;
	char arr[MAXFLDS][MAXFLDSIZE]={0x0};
	int recordcnt=0;	
	FILE *in=fopen(argv[1],"r");         /* open file on command line */
	
	if(in==NULL)
	{
		perror("File open error");
		exit(EXIT_FAILURE);
	}
	while(fgets(tmp,sizeof(tmp),in)!=0) /* read a record */
	{
	    int i=0;
	    recordcnt++;
		printf("Record number: %d\n",recordcnt);
		parse(tmp,",",arr,&fldcnt);    /* whack record into fields */
		for(i=0;i<fldcnt;i++)
		{                              /* print each field */
			printf("\tField number: %3d==%s\n",i,arr[i]);
		}
	}
    fclose(in);
    return 0;	
}

[Ancient Dragon]

line 12: should be this: while(p) Your program gets segment violation when strtok() returns NULL.

>>I realize its probably overkill for my purpose so if anyone could point me to a simpler solution that would be appreciated too.
In C language that's about the best anyone can do.

[stilllearning]

I am not sure if this is needed or not, but most CSV files have a header record, which is essentially the names of the columns separated by commas. If you are parsing an actual CSV file, you will need to take that into account also.

[Duoas]

> I am not sure if this is needed or not, but most CSV files have a header record, which is essentially the names of the columns separated by commas. If you are parsing an actual CSV file, you will need to take that into account also.

That may be true for some, but the vast majority of CSV files in use have no such thing. Unlike something like an XML file, CSV files have no way to tell you what they contain. The reading program must know what to expect when reading any CSV. Even the assumption that CSV is textual data, or fields separated by commas or tabs, and other stuff, is entirely that, assumption.

If you like I'll dig up an old CSV parser I wrote that can handle anything and port it to C for you. (Remember, it can read and write any CSV file, but, again, you must know what that CSV file contains for it to be useful!)

[matt nagel]

Ahhh thanks for that, a silly mistake.

Duoas if you have it lying around Id love to take a look

Thanks in advance.

[Duoas]

Hey there, if you're still interested, don't give up.

I wrote it originally in Object Pascal, and I used a number of very powerful container classes that don't exist in C (...obviously). So I've been coding a replacement for them also... (It's kind of boring actually...)

I should be done pretty soon. Once I give it some basic testing I'll wrap the whole thing up for you and respond here again.