I don't understand what i'm doing wrong..

I'm unable to allocate memory for my array of structs.. Any clues to what i'm doing wrong? The

#include <stdio.h>
#include <io.h>
#include <fcntl.h>
#include <stdlib.h>
#include <conio.h>

typedef struct _head_data{
int iNoOfLn;
}HEAD;

typedef struct _line_data{
int iLnNo;
char achName[25];
}LINE;

int fetchData(HEAD *HD, LINE *LD){
int i = 0;

HD->iNoOfLn = 100; // Fetch header
// Allocate memory
if(!(LD = malloc(HD->iNoOfLn * sizeof(*LD)))){
printf("Error allocating memory\n");
exit(0);
}
// Read lines
for(i=0;i<HD->iNoOfLn;i++){
LD[i].iLnNo = i+1;
sprintf(LD[i].achName,"Item no: %03d", i+1);
}

return(0);
}

int main(){
HEAD HD;
LINE *LD = 0;
int i;

printf(!fetchData(&HD,LD) ? "OK\n" : "ERR\n");
for(i=0;i<HD.iNoOfLn;i++)
printf("No: %d, Name: %s\n",LD[i].iLnNo, LD[i].achName);
getch();
return(0);
}

didn't went throught the entire code ... but HD should be declared before you can use it

HD and LD are declared, but LD is a null pointer until HD is read. I then allocate memory using malloc. This doesn't work.. Suggestions?

The only interesting part of the code is this:

HD->iNoOfLn = 100; // Fetch header
// Allocate memory
if(!(LD = malloc(HD->iNoOfLn * sizeof(*LD)))){
printf("Error allocating memory\n");
exit(0);
}
// Read lines
for(i=0;i<HD->iNoOfLn;i++){
LD[i].iLnNo = i+1;
sprintf(LD[i].achName,"Item no: %03d", i+1);
}

hi knutso,

you need to pass a pointer to pointer to LD struct in order to return that to where are you calling it.
so instead of:
> int fetchData(HEAD *HD, LINE *LD){

use

Code:

---

int fetchData(HEAD *HD, LINE **LD) {
        int i = 0;

        HD->iNoOfLn = 100; // Fetch header
        // Allocate memory
        if(!(*LD = malloc(HD->iNoOfLn * sizeof(LINE)))) {
                printf("Error allocating memory\n");
                exit(0);
        }
        // Read lines
        for(i=0;i<HD->iNoOfLn;i++) {
                (*LD)[i].iLnNo = i+1;
                sprintf((*LD)[i].achName,"Item no: %03d", i+1);
        }

        return(0);
}

---

Code:

---

...
printf(!fetchData(&HD,&LD) ? "OK\n" : "ERR\n");
...

---

damyan

Off course! Thanks.