C program Reading from a text file and writing the sorted list into the same text file. What modifications can i do?

Question

The below program giving the following error when compiling:

./vpl_test: line 2: 18699 Segmentation fault (core dumped) ./solution

What could be the problem with the below C program ?

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

void sort(long *sorted, int count,long value){
    int i=0;
    sorted[count] = value;
    if(count == 0)return;
    for(i=count;i>=0;i--){
        if(value<sorted[i-1])
        sorted[i] = sorted[i-1];
        else break;
    }
    sorted[i]=value;
}

int main(int argc,char *argv[]){
    FILE *fp = NULL;
    long sorted[1024];
    long value;
    int count = 0;
    int i=0;
    fp = fopen("brandlist.txt","r+");
    //fp = fopen("brandlist.txt","w");
    if(NULL == fp){
        perror("fopen");
        exit(0);
    }
    while(!feof(fp)){
        fscanf(fp,"%ld\n",&sorted[i]);
        sort(sorted,count,value);
        ++count;
    }
    for(i=0;i<count;i++){
        fprintf(fp,"%ld\n",sorted[i]);
    }

    if(fp){
        fclose(fp);
        fp = NULL;
    }
}

Answer 1

I could not reproduce the segfault (probably because of being "lucky" or maybe because of having wrong input).
The problem I did have was wrong sorting and strange values in sorted output, I believe that the same problem causes all misbehaviours, including the segfault in your case.

Here is a commented version of your code, picking up from the excellent comments and adding the (many) necessary changes to work on strings instead of integers.
(Allow me this little rant: It would really have saved a lot of time to provide actual sample input from start.)
It does have no segfault (at least not for me), no missorting and no strange values. Output (i.e. new content of input file):

Damro
Duriyan
Evoks
Godrej
Luxxe
Nilkamal
Wipro
Zuari

Code:

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

typedef char brandname[20];

void sort(brandname *sorted, int count, brandname *value){
    int i=0;
    strncpy((char*)sorted[count], (char*)value, sizeof(brandname));
    if(count == 0) return;

    // picking up input by BLUEPIXY;
    // this probably prevents the segfault,
    // it definitly prevents strange values
    // appearing in the sorted result
    for(i=count;i>0;i--)
    {
        if(0>strncmp((char*)value, (char*)sorted[i-1],sizeof(brandname)))
            strncpy( (char*)sorted[i], (char*)sorted[i-1], sizeof(brandname));
            else break;
    }
    strncpy((char*)sorted[i], (char*)value, sizeof(brandname));
}
int main(int argc,char *argv[]){
    FILE *fp = NULL;
    brandname sorted[1024];
    brandname value;
    int count = 0;
    int i=0;
    fp = fopen("brandlist.txt","r+");
    //fp = fopen("brandlist.txt","w");
    if(NULL == fp){
        perror("fopen");
        exit(0);
    }
    // picking up input from cooments on feof
    // but also use the increasing "count"
    // instead of unchanging "i"
    while(1==fscanf(fp,"%s", value))
    {
        // use the read value inside "sorted[count]"
        sort(sorted, count, &value);
        ++count;
    }
    // do not append sorted to input
    rewind(fp);
    for(i=0;i<count;i++){
        fprintf(fp,"%s\n",sorted[i]);
    }

    if(fp){
        fclose(fp);
        fp = NULL;
    }

    // avoid a warning
    return 0;
}