C program to perform union operation on two arrays

A union is a special data type available in C programming language that allows to store different data types in the same memory location. Unions provide an efficient way of using the same memory location for multiple-purpose.

Union operation

If array 1 = { 1,2,3,4,6}

    Array 2 = {1,2,5,6,7}

Then, union of array1 and array 2 is

Array1 U array 2 = {1,2,3,4,6} U {1,2,5,6,7}

                              = {1,2,3,4,5,6,7}

Set of all elements without repetition is called union.

The logic for union is as follows −

for(i=0;i<size1;i++){    uni[j]=a[i];    j++; } for(i=0;i<size2;i++){    uni[j]=b[i];    j++; }

The logic for removing repeated elements is as follows −

int removerepeated(int size,int a[]){    int i,j,k;    for(i=0;i<size;i++){       for(j=i+1;j<size;){          if(a[i]==a[j]){             for(k=j;k<size;k++){                a[k]=a[k+1];             }             size--;          }else{             j++;          }       }    }    return(size); }

Program

Following is the C program to perform union operation on two arrays −

 Live Demo

#include<stdio.h> int removerepeated(int size,int a[]); void sort(int size,int a[]); main(){    int i,size1,size2,size,j=0,k;    printf("Enter size of an array1
");    scanf("%d",&size1);    printf("Enter size of an array2
");    scanf("%d",&size2);    int a[size1],b[size2],uni[size1+size2];    printf("Enter numbers for array 1
");    for(i=0;i<size1;i++){       scanf("%d",&a[i]);    }    printf("Enter numbers for array 2
");    for(i=0;i<size2;i++){       scanf("%d",&b[i]);    }    //union start    for(i=0;i<size1;i++){       uni[j]=a[i];       j++;    }    for(i=0;i<size2;i++){       uni[j]=b[i];       j++;    }    //Sorting    sort(size1+size2,uni);    //Remove repeated elements    size=removerepeated(size1+size2,uni);    printf("Array afetr Union 
");    for(i=0;i<size;i++){       printf("%d
",uni[i]);    }    //Sorting } int removerepeated(int size,int a[]){    int i,j,k;    for(i=0;i<size;i++){       for(j=i+1;j<size;){          if(a[i]==a[j]){             for(k=j;k<size;k++){                a[k]=a[k+1];             }             size--;          }else{             j++;          }       }    }    return(size); } void sort(int size,int a[]){    int i,j,temp;    for(i=0;i<size;i++){       for(j=i+1;j<size;j++){          if(a[i]>a[j]){             temp=a[i];             a[i]=a[j];             a[j]=temp;          }       }    } }

Output

When the above program is executed, it produces the following result −

Enter size of an array1 4 Enter size of an array2 3 Enter numbers for array 1 1 2 3 4 Enter numbers for array 2 3 5 6 Array after Union 1 2 3 4 5 6