arrays - Read a large CSV File and storing the content in C language -

i learning c programming , got stuck 1 code. want read , store large csv file of around 10000 rows , 5 columns, each coloumn having names time, time_diff, sn,rs, fr.

i wrote code it. wanted read different columns, used strtok function read line , store in different variables. read file , print content on screen. not getting how store contents in array.

i tried make array of structures , store values in these array, somehow not working. used random value of int variable i, check if works or not.

can please explain how store different variables in array , how call them back. if want print sn[1000], how store it. following code:

#include <stdio.h> #include <stdlib.h> #include <string.h> #define buffer_size 1024*1024 struct filedata {     char *time;     int time_diff;     int sn;     int rs;     int fr; };   struct filedata data[10000];  int main () {     //char buffer [buffer_size];     char *buffer;     file *fp;     char *token;     int filesize;     int i;      if ((fp=fopen("testfile.csv", "r"))==null)     {         printf ("file cannot opened");     }       buffer = (char*)malloc (buffer_size);      if (buffer == 0)     {     printf("error: out of memory");     return 1;     }       fgets(buffer, buffer_size, fp);     token = strtok(buffer, ";");       while (token !=null)     {     printf (" \t%s", token);     token = strtok (null, ";");     }     (i=0; i<4;i++)     {          while ((fgets(buffer, filesize, fp)))          {               token = strtok(buffer, ";");             data[i].time = token;              token = strtok(null, ";");             data[i].time_diff = token;              token = strtok(null, "; ");             data[i].sn = atoi(token);               token = strtok(null, "; ");             data[i].rs = atoi(token);               token = strtok(null, "; ");             data[i].fr = atoi(token);                printf("\t%s\t%s\t%d\t%d\t%d\t\n", data[i].time, data[i].time_diff, data[i].sn, data[i]. rs, data[i]. fr);           }      }       free (buffer);   return 0;  } 

thanks in advance help

your code had several issues. please find corrected version below.

some of issues had:

1. not saving result of strtok in filedata.time. need copy string, not use assignment. need allocate space filedata.time using malloc (don't forget free each filedata.time allocated in such case) , copy result of strtok there; alternatively can use fixed length strings if like.

2. using wrong format specifier in last printf data[i].time_diff.

3. not using atoi time_diff.

4. use of uninitialized variables. used filesize variable without initializing it.

   struct filedata  {     char *time; /*increase if or use dynamic memory*/     int time_diff;     int sn;     int rs;     int fr; }; struct filedata data[arr_size];  int main(int argc, char *argv[]) {      char *buffer;     file *fp;     char *token;     int filesize = 0;     int = 0, j=0;      if ((fp=fopen("c:\\test.txt", "r"))==null)     {         printf ("file cannot opened");         return 1;     }       buffer = malloc (buffer_size);     if (buffer == null)     {         printf("error: out of memory");         return 1;     }       fgets(buffer, buffer_size, fp);     token = strtok(buffer, ";");       while (token !=null)     {         printf (" \t%s", token);         token = strtok (null, ";");     }      while ((fgets(buffer, buffer_size, fp)))     {         if(i>=arr_size) break;          data[i].time=malloc(256); // use constant(or define) more suitable         token = strtok(buffer, ";");         strcpy(data[i].time,token);          token = strtok(null, ";");         data[i].time_diff = atoi(token);          token = strtok(null, "; ");         data[i].sn = atoi(token);           token = strtok(null, "; ");         data[i].rs = atoi(token);           token = strtok(null, "; ");         data[i].fr = atoi(token);           printf("\t%s\t%d\t%d\t%d\t%d\t \n", data[i].time, data[i].time_diff, data[i].sn, data[i].rs, data[i].fr);         i++;       }      // note: don't forget free each  data[i].time     // allocated space, e.g.     for(j =0;j<i; j++) free(data[j].time);      free(buffer);     return 0;    }