Function SegFault with Arrays of Structs - c

Question

I am using this function:
int times_on_table(char *search,struct table index[],int wct){
int ct=0,num=0;
while(ct<wct){
if(strcmp(search,(index[ct].label))==0) {
num++;
}
ct++;
}
return num;
}
to search through an array of structs and find all the times a certain string is stored in the array and returns the number of times the string occurs. Whenever i use this function inside main:
/*EDIT: i had a main from the wrong program my apologies*/
int main(int argc, char **argv){
int numwds=get_num_words(argv[1]);
struct table index[numwds];
int a;
struct cmd_ops symbol[22];
store(argv[1],index,numwds);
ops_gen(symbol);
int b=times_on_table("in",index,numwds);
printf("%d",b);
}
the code works fine. However, when i try to use it inside certain functions like this one
struct table* store(char *filename,struct table index[]) {
FILE *fp;
fp=fopen(filename,"r");
char *a;int d=0,e=0,t=0;
a=malloc(60);
int wordcount=get_num_words(filename);
while(d<wordcount){
fscanf(fp,"%s",a);
if ((index[d].label=strdup(a))==NULL)
break;
index[d].word_num=d;
times_on_table("this",index,wordcount);/*when i comment this out
of my code it runs fine*/
index[d].address=findline(filename,index[d].label,wordcount,index,t);
d++;
}
free(a);
}
the code does not run and gives me a segmentation fault. Any thoughts?
EDIT: I don't know if this helps but when i get the segfault, it happens before even the first line of code in main is executed.
EDIT:here is the other function that causes a segfault when times_on_table() is called:
int findline(char *filename,char *check,int wordcount,struct table index[],int t){
char *a;
a=malloc(60);
int b=line_count(filename);
int ch;
fpos_t pos;
int line=0,wd=0,loc,s=0,c=1,times;
times=times_on_table(check,index,wordcount);
FILE *fp;
fp=fopen(filename,"r");
int list[wordcount];
while(c<=b){
fscanf(fp,"%s",a);
fgetpos(fp,&pos);
ch=fgetc(fp);ch=fgetc(fp);
if(strcmp(a,check)==0){
if(times==0)
return line;
else
times--;
}
if(ch==10){
line++;c++;
}
else
fsetpos(fp,&pos);
}
return line;
}
it was in this function that i first added times_on_table(), and had the segmentation fault keep my program from running.

Answer 1

Here
while(d<wordcount){
fscanf(fp,"%s",a);
if ((index[d].label=strdup(a))==NULL)
break;
index[d].word_num=d;
times_on_table("this",index,wordcount);
you try to count the occurrences of "this" in a wordcount long array, but you have only filled d+1 slots of the array. The other slots may contain garbage, and then accessing index[ct].label is likely to cause a segmentation fault when ct > d.

Answer 2

It is very likely you are going past the array index. These two lines do not really match up (from the code you have shared with us :
int wordcount=get_num_words(filename);
times_on_table("this",index,wordcount);
(wordcount I assume counts something in filename which is passed in as the first parameter, but it seems irrelevant to your struct table index[])
So the parameter being passed in struct table index[], is probably a different size than the value you are storing into wordcount. I would suggest you pass in the array size as a parameter to the store function and use that as you would in your working main example. example
struct table* store(char *filename,struct table index[], int structSize){
....
times_on_table("this",index,structSize); //replace b from the call in main
}

Answer 3

It may be related with setting the "index[d].label" properly. Try to print all the labels outside the times_on_table() function without comparing them with anything.