Reading a csv file in c - c

Question

I'm trying to read a csv file that contains 9 columns each having information about a person. I'm supposed to store the data in a hash table and create a function to look up data based on the surname. This is my code
#include<stdio.h>
#include<stdlib.h>
#include <string.h>
#include <ctype.h>
#define tablesize 27
#define entries 21
unsigned long int collisions = 0;
typedef struct {
char id[20];
char depid[10];
char surname[20];
char forename[20];
char age[2];
char ptype[20];
char gender[6];
char nation[20];
char religion[20];
char occupation[20];
}dict;
dict* hashTable[tablesize]= {NULL};
unsigned long int hash_function(char* s){
unsigned long int hash = 0;
while(*s){
hash = hash + *s;
s++;
}
return hash%tablesize;
}
void print_table(){
for(unsigned long int i=0;i<tablesize;i++){
if(hashTable[i]==NULL){
printf("%d\t---\t---\n",i);
}
else{
printf("%d\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\n",i,hashTable[i]->id,hashTable[i]->depid,hashTable[i]->surname,hashTable[i]->forename,hashTable[i]->age
,hashTable[i]->ptype,hashTable[i]->gender,hashTable[i]->nation,hashTable[i]->religion,hashTable[i]->occupation);
}
}
}
void insert(dict *d){
unsigned long int ind = hash_function(d->surname);
for(unsigned long int i=0;i<tablesize;i++){
unsigned long int try = (ind+i)%tablesize;
if(hashTable[try]==NULL){
hashTable[try] = d;
return;
}
else{
collisions++;
}
}
}
void printvalues(unsigned long int i){
printf("%d\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\n",i,hashTable[i]->id,hashTable[i]->depid,hashTable[i]->surname,hashTable[i]->forename,hashTable[i]->age
,hashTable[i]->ptype,hashTable[i]->gender,hashTable[i]->nation,hashTable[i]->religion,hashTable[i]->occupation);
}
void search(char* name){
unsigned long int ind = hash_function(name);
unsigned long int f=1;
for(unsigned long int i=0;i<tablesize;i++){
unsigned long int try = (ind+i)%tablesize;
if(hashTable[try]!=NULL&&strcmp(hashTable[try]->surname,name)==0){
printvalues(try);
f=0;
}
}
if(f==1)
printf("%s not in table\n",name);
return;
}
int main(){
FILE *fp = fopen("truncated.csv","r");
if(!fp){
printf("Error");
return 0;
}
char buff[1024];
unsigned long int row = 0, column = 0;
dict values[entries];
unsigned long int i=0;
while(fgets(buff,1024,fp)){
column=0;
row++;
if(row==1){
continue;
}
char *field = strtok(buff,",");
while(field){
if(column==0){
strcpy(values[i].id,field);
}
if(column==1){
strcpy(values[i].depid,field);
}
if(column==2){
strcpy(values[i].surname,field);
}
if(column==3){
strcpy(values[i].forename,field);
}
if(column==4){
strcpy(values[i].age,field);
}
if(column==5){
strcpy(values[i].ptype,field);
}
if(column==6){
strcpy(values[i].gender,field);
}
if(column==7){
strcpy(values[i].nation,field);
}
if(column==8){
strcpy(values[i].religion,field);
}
if(column==9){
strcpy(values[i].occupation,field);
}
field = strtok(NULL,",");
column++;
}
i++;
}
fclose(fp);
for(unsigned long int i=0;i<entries;i++){
insert(&values[i]);
}
//printvalues(values);
//print_table();
while(1){
printf("Enter term to get frequency or type 'quit' to escape:");
char name[20];
scanf("%s",name);
if(strcmp(name,"quit")==0)
return 0;
search(name);
}
return 0;
}
The problem I'm facing is that i have two csv files, one containing 60000 entries and one containing only 21 entries. When i read the smaller file, the code works just fine. But i am getting no output whatsoever for the bigger file. Any ideas? Thanks in advance.

Answer 1

In your code, you have only space for 21 entries (line #define entries 21)
So you'll parse 22th line and more in the big file, you'll try to write into a forbidden place. From this point, you enter in UB zone.
Solution: make values dynamic.
int count = 0;
dict *values = NULL;
while(fgets(buff,1024,fp)){
++count;
dict * tmp = realloc(values, sizeof (dict) * count);
if (NULL == tmp) {
perror("realloc");
free(values);
exit(1);
} else {
values = tmp;
}
and after the while loop:
free(values);