How to memory allocate a pointer inside a pointer? - c

Question

I'm new in C programming (my main area is java) and in java there exists the ArrayList which I can make like
ArrayList<Class> arraylist = new ArrayList<Class>();
where my class Class can have several items, such as int, or string.
In c, I found I cannot do that but need to do something like that, so I did this
typedef struct vectorObject {
int myInt;
char *charPointer;
} vectorObject;
I define a pointer of my structure like this:
vectorObject *listVectorObject;
and using
#define MAX_FILE_SIZE 50000
when I want to allocate the memory of that, I use this:
int i;
listVectorObject = malloc(MAX_FILE_SIZE);
if (listVectorObject == NULL ) {
printf("Out of memory1\n");
exit(1);
}
for (i = 0; i < MAX_FILE_SIZE; i++) {
listVectorObject[i].charPointer= malloc(MAX_FILE_SIZE);
if (listVectorObject[i].charPointer == NULL ) {
printf("Out of memory2\n");
exit(1);
}
}
The problem is I always get a
Out of Memory2
I already tried everything and I cannot find where my mistake is. Could you please help me?
Thanks!!

Answer 1

I don't think you want 50000 vectorObjects each with 50000 bytes char-buffer.
So look at this:
first making a list of 1000 vectorObjects
then for each of those allocating a memory chunk to the char-pointer
.
int i, howmany= 1000;
vectorObject *listVectorObject = malloc(sizeof(vectorObject)*howmany); // list of 1000 vectorObjects
if (listVectorObject == NULL ) {
printf("Out of memory1\n");
exit(1);
}
// one file-size char-pointer for each vector object above
for (i = 0; i<howmany; i++) {
listVectorObject[i].charPointer= malloc(MAX_FILE_SIZE);
if (listVectorObject[i].charPointer == NULL ) {
printf("Out of memory2\n");
exit(1);
}
}