C Program to Find Union and Intersection of Two Arrays

This C Program finds union & intersection of 2 arrays. Union here refers to the set of all the elements of the 2 arrays. Intersection here refers to the set of elements which are in both the arrays.

Here is source code of the C Program to find union & intersection of 2 arrays. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C Program to Find Union & Intersection of 2 Arrays

```
 */
```
```
#include <stdio.h>
```
```
#define SIZE 5
```
```
 
```
```
void get_value(int arr[]);
```
```
void print_value(int arr[], int n);
```
```
void function_sort(int arr[]);
```

int find_intersection(int array1[], int array2[], int intersection_array[]);

int find_union(int array1[], int array2[], int union_array[]);

```
 
```
```
void main()
```
```
{
```

    int array1[SIZE], array2[SIZE], intersection_array[SIZE], union_array[SIZE*2];

```
    int num_elements;
```
```
 
```
```
    //input elements of Array1
```

    printf("\n Enter the elements of Array 1: n");

```
    get_value(array1);
```

    printf("\n\n Elements of Array 1: ");

```
    print_value(array1, SIZE);
```
```
 
```
```
    //Sort array 1
```
```
    function_sort(array1);
```

    printf("nnSorted elements of Array 1: ");

```
    print_value(array1, SIZE);
```
```
 
```
```
    //input elements of Array2
```

    printf("nnEnter the elements of Array 2: n");

```
    get_value(array2);
```

    printf("\n\n Elements of Array 2: ");

```
    print_value(array2, SIZE);
```
```
 
```
```
    //Sort array 2
```
```
    function_sort(array2);
```

    printf("\n\nSorted elements of Array 2: ");

```
    print_value(array2, SIZE);
```
```
 
```
```
    //Find Intersection
```

    num_elements = find_intersection(array1, array2, intersection_array);

```
    printf("\n\n Intersection is: ");
```

    print_value(intersection_array, num_elements);

```
 
```
```
    //Find Union
```

    num_elements = find_union(array1, array2, union_array);

```
    printf("\n\n Union is: ");
```

    print_value(union_array, num_elements);

```
}
```
```
 
```
```
void get_value(int arr[])
```
```
{
```
```
    int i, j;
```
```
    for (i = 0; i < SIZE; i++)
```
```
    {
```
```
        j = i + 1;
```

        printf("\n Enter element %d: ", j);

```
        scanf("%d", &arr[i]);
```
```
    }
```
```
}
```
```
 
```
```
void print_value(int arr[], int n)
```
```
{
```
```
    int i;
```
```
    printf("{ ");
```
```
    for (i = 0; i < n; i++)
```
```
    {
```
```
        printf("%d ", arr[i]);
```
```
    }
```
```
    printf("}");
```
```
}
```
```
 
```
```
void function_sort(int arr[])
```
```
{
```
```
    int i, j, temp, swapping;
```
```
 
```
```
    for (i = 1; i < size; i++)
```
```
    {
```
```
        swapping = 0;
```
```
        for (j = 0; j < size-i; j++)
```
```
        {
```
```
            if (arr[j] > arr[j+1])
```
```
            {
```
```
                temp = arr[j];
```
```
                arr[j] = arr[j + 1];
```
```
                arr[j + 1] = temp;
```
```
                swapping = 1;
```
```
            }
```
```
        }
```
```
        if (swapping == 0)
```
```
        {
```
```
            break;
```
```
        }
```
```
    }
```
```
}
```
```
 
```

int find_intersection(int array1[], int array2[], int intersection_array[])

```
{
```
```
    int i = 0, j = 0, k = 0;
```
```
    while ((i < size) && (j < size))
```
```
    {
```
```
        if (array1[i] < array2[j])
```
```
        {
```
```
            i++;
```
```
        }
```
```
        else if (array1[i] > array2[j])
```
```
        {
```
```
            j++;
```
```
        }
```
```
        else
```
```
        {
```

            intersection_array[k] = array1[i];

```
            i++;
```
```
            j++;
```
```
            k++;
```
```
        }
```
```
    }
```
```
    return(k);
```
```
}
```
```
 
```

int find_union(int array1[], int array2[], int union_array[])

```
{
```
```
    int i = 0, j = 0, k = 0;
```
```
    while ((i < SIZE) && (j < SIZE))
```
```
    {
```
```
        if (array1[i] < array2[j])
```
```
        {
```
```
            union_array[k] = array1[i];
```
```
            i++;
```
```
            k++;
```
```
        }
```
```
        else if (array1[i] > array2[j])
```
```
        {
```
```
            union_array[k] = array2[j];
```
```
            j++;
```
```
            k++;
```
```
        }
```
```
        else
```
```
        {
```
```
            union_array[k] = array1[i];
```
```
            i++;
```
```
            j++;
```
```
            k++;
```
```
        }
```
```
    }
```
```
    if (i == SIZE)
```
```
    {
```
```
        while (j < SIZE)
```
```
        {
```
```
            union_array[k] = array2[j];
```
```
            j++;
```
```
            k++;
```
```
        }
```
```
    }
```
```
    else
```
```
    {
```
```
        while (i < SIZE)
```
```
        {
```
```
            union_array[k] = array1[i];
```
```
            i++;
```
```
            k++;
```
```
        }
```
```
    }
```
```
    return(k);
```
```
}
```

$ cc pgm98.c
$ a.out
 
Enter the elements of Array 1:
 
Enter element 1: 12
 
Enter element 2: 34
 
Enter element 3: 23
 
Enter element 4: 56
 
Enter element 5: 45
 
 
Elements of Array 1: { 12 34 23 56 45 }
 
Sorted elements of Array 1: { 12 23 34 45 56 }
 
Enter the elements of Array 2:
 
Enter element 1: 34
 
Enter element 2: 56
 
Enter element 3: 12
 
Enter element 4: 78
 
Enter element 5: 66
 
 
Elements of Array 2: { 34 56 12 78 66 }
 
Sorted elements of Array 2: { 12 34 56 66 78 }
 
Intersection is: { 12 34 56 }
 
Union is: { 12 23 34 45 56 66 78 }

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If you wish to look at other example programs on Arrays, go to C Programming Examples on Arrays. If you wish to look at programming examples on all topics, go to C Programming Examples.

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