Array of Structures in C missing data? -

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i designing program in c. part of program involves reading table of data relating periodic table , elements file, , putting in structure.

so far, it's working rather well. however, reason, when try display array, couple of elements don't show up, instead blanks. show earlier in code, though.

main.c

main() {     struct periodic *tableptr;     tableptr = createtable();     printf("%d\t",(tableptr+90)//prints "pa" here expected     int i;     for(i=0;i<num_elements;i++){         printf("%d\t%s\n",i,(tableptr+90)->sym);//prints i, blank.     }   }

periodic.c (creates table)

#include "periodic.h" #include <stdio.h>  struct periodic *createtable(){      char format[] ="%d\t%s[3]\t \                          %s[20]\t%f\t \                          %s[100]\t%f\t \                          %d\t%f\t%d\t \                          %d\t%d\t%s[20]\t \                          %s[7]\t%s[17]\t \                          %d\t%d\t%f\t \                          %s[40]\n)";       struct periodic period_table[num_elements];     struct periodic *tableptr = period_table;     file *fp;     fp = fopen("periodictable.csv","r");      char buff[200];      struct periodic *initptr = tableptr;     while(fgets(buff,sizeof(buff),fp)){         sscanf(buff,format,&(tableptr->num),&(tableptr->sym),&(tableptr->name),&(tableptr->weight),&(tableptr->config),&(tableptr->neg),&(tableptr->ion_rad),&(tableptr->vdw_rad),&(tableptr->ie_1),&(tableptr->ea),&(tableptr->oxi_st),&(tableptr->stn_st),&(tableptr->melt),&(tableptr->boil),&(tableptr->dens),&(tableptr->type));         tableptr++;     }      fclose(fp);     return initptr;  }

i can give more information needed.

you have:

struct periodic *tableptr = period_table;

here, tableptr points array defined locally in function. , return tableptr function. when function returns, array destroyed. hence, calling function has dangling pointer.

referencing dangling pointer leads undefined behavior.

you need allocate memory heap, return pointer dynamically allocated memory, , deallocate memory in calling function.

struct periodic *tableptr = malloc(sizeof(*tableptr)*num_elements);

and in main, call

free(tableptr);

before function ends.

also, add explicit return type main.

int main()  {    ... }

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