Question

Would this be the proper way to extend a structure array?

typedef struct { int x,y,z;} student_record;

int main(){

student_record data_record[30];       // create array of 30 student_records
num_of_new_records = 5;

data_record = realloc(data_record,(sizeof(data_record) + (sizeof(student_record)*num_of_new_records)));

// do I now have an array of 35 student_records???

Answer 1

No – you can’t assign to an array. Your code won’t even compile – did you try it?

If you want to realloc() you need to have used malloc() (or one of its relatives):

student_record *data_record = malloc(sizeof(student_record) * 30);

You probably shouldn’t be assigning the return value of realloc() back to the original variable, either. If it fails for some reason, you’ll lose the original pointer and leak that memory.