C Program to Merge Two Arrays

How to write a C Program to Merge Two Arrays with example?. Before going into this C Program to Merge Two Arrays example.

C Program to Merge Two Arrays Example 1

This program to merge two arrays in c allows the user to enter the Array size, Array elements of two different arrays. Next, it will merge two arrays one after the other using For Loop.

/* C Program to Merge Two Arrays using For Loop */
#include<stdio.h>
 
int main()
{
 	int aSize, bSize, mSize, i, j;
	int a[10], b[10], Merged[20];
  
 	printf("\n Please Enter the First Array Size  :  ");
 	scanf("%d", &aSize);
 
 	printf("\nPlease Enter the First Array Elements :  ");
 	for(i = 0; i < aSize; i++)
  	{
      	scanf("%d", &a[i]);
  	}
  	printf("\n Please Enter the Second Array Size  :  ");
 	scanf("%d", &bSize);
   
 	printf("\nPlease Enter the Second Array Elements  :  ");
 	for(i = 0; i < bSize; i++)
  	{
      	scanf("%d", &b[i]);
  	}
  	
  	for(i = 0; i < aSize; i++)
  	{
      	Merged[i] = a[i];
  	}
  	
	mSize = aSize + bSize;
 
 	for(i = 0, j = aSize; j < mSize && i < bSize; i++, j++)
  	{
  		Merged[j] = b[i];
  	}
 
 	printf("\n a[%d] Array Elements After Merging \n", mSize); 
 	for(i = 0; i < mSize; i++)
  	{
    	printf(" %d \t ",Merged[i]);
  	}
 
  	return 0;
}
C Program to Merge Two Arrays using For Loop 1

In this C merge two arrays example, below For loop will help to iterate every cell present in a[3] array. Condition inside the for loops (i < Size) will ensure the compiler, not to exceed the array limit. Please refer to Array in C article to understand the concept of Array size, index position, etc.

Inside the C Programming for loop, we are assigning each and every arr array element to Merged array.  It means, Merged[0] = arr[0], Merged[1] = arr[1], Merged[2] = arr[2], Merged[3] = arr[3], Merged[4] = arr[4]

for(i = 0; i < aSize; i++)
{
      	Merged[i] = a[i];
}

Now merged[3] = {10, 20, 30}

In the next line, We have one more for loop to insert the second array elements into the Merged array

for(i = 0, j = aSize; j < mSize && i < bSize; i++, j++)
{
	Merged[j] = b[i];
}

From the above Program to Merge Two Arrays in C screenshot, you can observe that Second array elements are b[4] = {15, 25, 35, 45}

First Iteration: for(i = 0, j = aSize; j < mSize && i < bSize; i++, j++)
for (i = 0, j = 3; 3 < 7 && 0 < 4; 0++, 3++)
The condition (3 < 7 && 0 < 4) is True.
Merged[j] = b[i]
Merged[3] = b[0]
Merged[3] = 15

Second Iteration: for (i = 1, j = 4; 4 < 7 && 1 < 4; 1++, 4++)
The condition (4 < 7 && 1 < 4) is True.
Merged[j] = b[i]
Merged[4] = b[1]
Merged[4] = 25

Third Iteration: for (i = 2, j = 5; 5 < 7 && 2 < 4; 2++, 5++)
The condition (5 < 7 && 2 < 4) is True.
Merged[j] = b[i]
Merged[5] = b[2]
Merged[5] = 35

Fourth Iteration: for (i = 3, j = 6; 6 < 7 && 3 < 4; 3++, 6++)
The condition (6 < 7 && 3 < 4) is True.
Merged[j] = b[i]
Merged[6] = b[3]
Merged[6] = 45

Fifth Iteration: for (i = 4, j = 7; 7 < 7 && 4 < 4; 4++, 7++)
The condition (7 < 7 && 4 < 4) is False. So, it will exit from the For Loop

Next, we used one more for loop to print the output. I suggest you to refer the Print Array Elements article to understand this for loop.

C Program to Merge Two Arrays Example 2

This merge two arrays program will merge two arrays. While Merging it will check which number is the least value and then insert the least number first

/* C Program to Merge Two Arrays */
#include<stdio.h>
 
int main()
{
 	int aSize, bSize, mSize, i, j, k;
	int a[10], b[10], Merged[20];
  
 	printf("\n Please Enter the First Array Size  :  ");
 	scanf("%d", &aSize);
 
 	printf("\nPlease Enter the First Array Elements :  ");
 	for(i = 0; i < aSize; i++)
  	{
      	scanf("%d", &a[i]);
  	}
  	printf("\n Please Enter the Second Array Size  :  ");
 	scanf("%d", &bSize);
   
 	printf("\nPlease Enter the Second Array Elements  :  ");
 	for(i = 0; i < bSize; i++)
  	{
      	scanf("%d", &b[i]);
  	}
  	
	mSize = aSize + bSize;
	
	i = 0;
	j = 0;
	
 	for(k = 0; k < mSize; k++)
  	{
  		if(i >= aSize || j >= bSize)
  		{
  			break;
	  	}
	  	if(a[i] < b[j])
	  	{
	  		Merged[k] = a[i];
	  		i++;
		}
		else
		{
			Merged[k] = b[j];
			j++;
		}
  	}
  	
  	while(i < aSize)
  	{
  		Merged[k] = a[i];
  		k++;
  		i++;
	}
	
  	while(j < bSize)
  	{
  		Merged[k] = b[j];
  		k++;
  		j++;
	}
	 
 	printf("\n a[%d] Array Elements After Merging \n", mSize); 
 	for(i = 0; i < mSize; i++)
  	{
    	printf(" %d \t ",Merged[i]);
  	}
 
  	return 0;
}

C Merge Two Arrays output

Please Enter the First Array Size  :  5

Please Enter the First Array Elements :  10 20 30 40 50

 Please Enter the Second Array Size  :  6

Please Enter the Second Array Elements  :  5 7 15 35 95 17

 a[11] Array Elements After Merging 
 5 	  7 	  10 	  15 	  20 	  30 	  35 	  40 	  50 	  95 	  17 	 

Program to Merge Two Arrays Example 3

This program to merge two arrays is same as above, but we used Functions concept to arrange the code

/* C Program to Merge Two Arrays using Functions */
#include<stdio.h>

void Merge_Array(int a[], int aSize, int b[], int bSize, int Merged[]);
 
int main()
{
 	int aSize, bSize, mSize, i, j, k;
	int a[10], b[10], Merged[20];
  
 	printf("\n Please Enter the First Array Size  :  ");
 	scanf("%d", &aSize);
 
 	printf("\nPlease Enter the First Array Elements :  ");
 	for(i = 0; i < aSize; i++)
  	{
      	scanf("%d", &a[i]);
  	}
  	printf("\n Please Enter the Second Array Size  :  ");
 	scanf("%d", &bSize);
   
 	printf("\nPlease Enter the Second Array Elements  :  ");
 	for(i = 0; i < bSize; i++)
  	{
      	scanf("%d", &b[i]);
  	}
  	
  	Merge_Array(a, aSize, b, bSize, Merged);
  	
	mSize = aSize + bSize;
	
	printf("\n a[%d] Array Elements After Merging \n", mSize); 
 	for(i = 0; i < mSize; i++)
  	{
    	printf(" %d \t ",Merged[i]);
  	}
 
  	return 0;
} 

void Merge_Array(int a[], int aSize, int b[], int bSize, int Merged[])
{
	int i, j, k, mSize;
	j = k = 0;
	mSize = aSize + bSize;
	
	for(i = 0; i < mSize;)
	{
		if(j < aSize && k < bSize)
		{
			if(a[j] < b[k])
			{
				Merged[i] = a[j];
				j++;
			}
			else
			{
				Merged[i] = b[k];
				k++;
			}
			i++;
		}
		else if(j == aSize)
		{
			while(i < mSize)
			{
				Merged[i] = b[k];
				k++;
				i++;
			}
		}
		else
		{
			while(i < mSize)
			{
				Merged[i] = a[j];
				j++;
				i++;
			}
		}
	}
}

 Please Enter the First Array Size  :  5

Please Enter the First Array Elements :  10 20 30 40 50

 Please Enter the Second Array Size  :  8

Please Enter the Second Array Elements  :  25 9 35 45 85 89 75 125

 a[13] Array Elements After Merging 
 10 	  20 	  25 	  9 	  30 	  35 	  40 	  45 	  50 	  85 	  89 	  75 	  125