problem at malloc

Question

i'm trying to apply malloc in my code, but still having a problem, there's an error saying : "request for member 'id' in something not a structure or union".

what i want to do is to use malloc instead of array.. and store the structure in each indices, i tried array[i]->id, but bunch of garbage character stored on my text file. I also increment i and didn't use loop, coz user may only input once... this is my code:

#include<stdio.h>
#include<stdlib.h>
struct studentinfo{
       char id[8];
       char name[30];
       char course[5];
}s1;
main(){
    int i=0;
    FILE *stream = NULL;
    stream = fopen("studentinfo.txt", "a+");    
    struct studentinfo *array[50];

    array[i] = (struct studentinfo*) malloc(sizeof(struct studentinfo));
       printf("Enter Student ID: ");
       scanf("%s", array[i].id);
       fflush(stdin);
       printf("Enter Student Name: ");
       gets(array[i].name);
       fflush(stdin);
       printf("Enter Student Course: ");
       scanf("%s", array[i].course);

       fprintf(stream, "\n%s,\t%s,\t%s", array[i].id, array[i].name, array[i].course);
       i++;
       fclose(stream);
       free(array);
    getch();
}

hope you can help me... thanks in advance :)

and change the gets() function because QUOTE "it is the devil's tool of creating buffer overflow"... http://stackoverflow.com/questions/4346598/gets-function-in-c — newbie, Dec 04 '10 at 04:23
Did you want to make an array of StudentInfo, or did you want to make an array of pointers to StudentInfo? Because you did the latter, and it seems like you wanted the former. — Karl Knechtel, Dec 04 '10 at 04:08

score 5 · Answer 1 · answered Dec 04 '10 at 04:04

5

You're accessing the properties incorrectly.

array[i]

is a pointer to a struct, so

array[i].id

is going to give you an error. Use

array[i]->id

to dereference.

answered Dec 04 '10 at 04:04

Elle H

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i use array[i]->id and free the space like newbie said... thnx guyz – iamanapprentice Dec 04 '10 at 04:27

score 3 · Accepted Answer · edited May 23 '17 at 12:08

3

You should initialize the array and free it like this: Am i using malloc properly?
Also... follow Zurahn's instruction.

edited May 23 '17 at 12:08

Community

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answered Dec 04 '10 at 04:03

newbie

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Good point (not the question he was asking, but a problem he'll have to fix nonetheless) – David Gelhar Dec 04 '10 at 04:08
fclose(stream); if(array[i] != NULL){ free(array);} this is what i use to free array... thnx – iamanapprentice Dec 04 '10 at 04:27

problem at malloc

2 Answers2