One array copying data to 2 other arrays using C pointers - c

Question

I am new to Programming and to Stack overflow, so forgive me if I make any mistakes. I have this program where one array of ints is split into two other arrays depending on if they are larger or smaller than a user inputted int. Right now all the smaller and larger arrays do is copy the first integer regardless of the number put in. Any suggestions/critiques?
/*
This program will separate an input array into two arrays. One array will be filled by
elements greater than a specified number and the other array will be filled by elements
less than the specified number.
*/
#include <stdio.h>
void separate(int *a, int n, int value, int *larger, int *size, int *smaller);
int main()
{
//Find size of array
int length;
int *length_pointer = &length;
printf("Enter the length of the array: ");
scanf("%d", length_pointer);
//Enter array elements
int array[length], *p;
printf("Enter %d numbers: ", length);
for(p = array; p < array + length; p++)
scanf("%d", p);
//Find separating value
int value;
printf("Enter the number to split the array: ");
scanf("%d", &value);
//Declare arrays and call function
int n = 0, larger[length], smaller[length];
separate(array, n, value, larger, length_pointer, smaller);
//Display the arrays
printf("%d\n", *smaller);
printf("%d", *larger);
return 0;
}
/*************************************************************************************
separate finds numbers larger than value in array a and stores them in array larger.
Numbers smaller than or equal to value will be stored in the smaller array.
size points to a variable in which the function will store the number of larger
numbers in the array.
*************************************************************************************/
void separate(int *a, int n, int value, int *larger, int *size, int *smaller)
{
// Delete later *smaller = *larger = *a;
for(a = &n; a < n + size; a++)
if(a[n] > value)
{
larger = &a[n];
}
else if(a[n] <= value)
smaller = &a[n];
return;
}

Answer 1

I modified a bit your code to reach your goal. In order to get array size from user input under C99, you need to dynamically assign it e.g. by calloc(elements_number, element_size_in_bytes) when your program runs. Don't forget to free assigned memory to avoid memory leaks. Like below:
int* array = calloc(user_input, sizeof(int));
...
//some code
...
free(array);
Your separate function looks a bit complex. This part is wrong:
for(a = &n; a < n + size; a++)
What you are doing here is making a point to integer n. a does not point anymore to a source array. So making a call like a[n] when a is &n is like (&n)[n]. n is not changing value also, because you increment pointer to n, not the value it points to.
Next if you want to display array elements do it by using loop, like I did below.
I could not find the purpose of n parameter in your separate function. I used it as amount of real elements in larger array, so I don't have to print all elements.
I hope this answer meats your expectations.
#include <stdio.h>
#include <stdlib.h>
void separate(int *a, int *larger_count, int value, int *larger, int size, int *smaller);
int main()
{
//Find size of array
int length;
int *length_pointer = &length;
printf("Enter the length of the array: ");
scanf("%d", length_pointer);
//Enter array elements
int*array = calloc(*length_pointer, sizeof(int));
int*p;
printf("Enter %d numbers: ", length);
for(p = array; p < array + length; p++)
scanf("%d", p);
//Find separating value
int value;
printf("Enter the number to split the array: ");
scanf("%d", &value);
//Declare arrays and call function
int *larger = calloc(*length_pointer, sizeof(int));
int *smaller = calloc(*length_pointer, sizeof(int));
int larger_count = 0;
separate(array, &larger_count, value, larger, length, smaller);
for (int i = 0 ; i < larger_count ; ++i)
{
printf("%d ", larger[i]);
}
printf("\n");
for (int i = 0 ; i < length - larger_count; ++i)
{
printf("%d ", smaller[i]);
}
printf("\n");
free(array);
free(larger);
free(smaller);
return 0;
}
/*************************************************************************************
separate finds numbers larger than value in array a and stores them in array larger.
Numbers smaller than or equal to value will be stored in the smaller array.
size points to a variable in which the function will store the number of larger
numbers in the array.
*************************************************************************************/
void separate(int *a, int *larger_count, int value, int *larger, int size, int *smaller)
{
for(int x = 0, y = 0, z = 0; x < size; x++)
{
if (a[x] > value)
{
larger[y] = a[x];
y++;
*larger_count = y;
} else
{
smaller[z] = a[x];
z++;
}
}
}