C Program to Swap Two Arrays Without Using Temp Variable

In this article We are going to show you, C Program to Swap two Arrays without using Temp variable. Instead of using third variable we are going to use Arithmetic Operators and Bitwise Operators.

C Program to Swap Two Arrays Without Using Temp Variable

In this C program, Instead of using the temp or third variable to swap two arrays We are going to use Arithmetic Operators in C.

/* C Program to Swap Two Arrays Without Using Temp Variable */
#include<stdio.h>

int main()
{
 int Size, i, a[10], b[10], Temp[10];
  
 printf("\nPlease Enter the Size of the Array\n");
 scanf("%d", &Size);
 
 printf("\nPlease Enter the First Array Elements\n");
 for(i = 0; i < Size; i++)
  {
      scanf("%d", &a[i]);
  }
   
 printf("\nPlease Enter the Second Array Elements\n");
 for(i = 0; i < Size; i ++)
  {
      scanf("%d", &b[i]);
  }

 //Swapping two Arrays 
 for(i = 0; i < Size; i++)
  {
    a[i] = a[i] + b[i];
    b[i] = a[i] - b[i]; 
    a[i] = a[i] - b[i];
  }

 printf("\n a[%d] Array Elements After Swapping \n", Size); 
 for(i = 0; i < Size; i ++)
  {
      printf(" %d \t ",a[i]);
  }

printf("\n\n b[%d] Array Elements After Swapping \n", Size); 
 for(i = 0; i < Size; i ++)
  {
      printf(" %d \t ",b[i]);
  }

  return 0;
} 

OUTPUT

ANALYSIS
In this Program, We declared 3 arrays or One dimensional arrays a, b and Temp

Below printf statement asks the User to enter the arrays a, b size (Number of elements. For instance 4 elements = a[4])

printf("\n Please Enter the Size of the Array\n");

Below scanf statement will assign the user entered values to Size variable.

scanf("%d", &Size);

Below for loop will helps to iterate each and every cell present in the a[3] array. Condition inside the for loops (i < Size)) will ensure the compiler, not to exceed the array size. Otherwise the array will overflow

scanf statement inside the for loop will store the user entered values in every individual array element such as a[0], a[1], a[2]

for(i = 0; i < Size; i++)
  {
      scanf("%d", &a[i]);
  }

Below for loop will helps to iterate each and every cell present in the b[2][3] matrix.

for(i = 0; i < Size; i++)
  {
      scanf("%d", &b[i]);
  }

User inserted values are
a[3] = {20, 50, 80} and
b[3] = {10, 35, 65}

First Iteration
The value of i will be 0 and the condition (i < 3) is True. So, it will start executing the statements inside the loop until the condition fails.
a[i] = a[i] + b[i];
a[0] = a[0] + b[0] = 20 + 10 = 30

b[i] = a[i] – b[i];
b[0] = a[0] – b[0] = 30 – 10 = 20

a[i] = a[i] – b[i];
a[0] = a[0] – b[0] = 30 – 20 = 10

Second Iteration
The value of i will be 1 and the condition (i < 3) is True.
a[1] = a[1] + b[1] = 50 + 35 = 85
b[1] = a[1] – b[1] = 85 – 35 = 50
a[1] = a[1] – b[1] = 85 – 50 = 35

Third Iteration
The value of columns will be 2 and the condition (i < 3) is True.
a[2] = a[2] + b[2] = 80 + 65 = 145
b[2] = a[2] – b[2] = 145 – 65 = 80
a[2] = a[2] – b[2] = 145 – 80 = 65

After the increment the value of columns will be 3 and the condition (i < 3) will fail. So it will exit from the loop.
Next for loop,

for(i = 0; i < Size; i ++)
  {
      printf(" %d \t ",a[i]);
  }

Will traverse as we explained above but instead of swapping two array number, it will display the values inside the a[i] array using the printf statements array.
Next for loop,

for(i = 0; i < Size; i ++)
  {
      printf(" %d \t ",b[i]);
  }

Will traverse as we explained above but instead of swapping two array number, it will display the values inside the b[i] array using the printf statements array.
The final output of the a[i] Array is:
a[3] = {10, 35, 65}{20, 50, 80}

The final output of the b[i] Array is:
b[3] = {20, 50, 80}

NOTE: Although we can swap two arrays using multiplication and division approach but they may produce strange values if we are working with larger integer values or if any of the integer value is 0

C Program to Swap Two Arrays Using Bitwise Operator

In this C program, Instead of using the temp or third variable to swap two arrays We are going to use Bitwise OR Operator.

/* C Program to Swap Two Arrays Without Using Temp Variable */

#include<stdio.h>

int main()
{
 int Size, i, a[10], b[10], Temp[10];
  
 printf("\nPlease Enter the Size of the Array\n");
 scanf("%d", &Size);
 
 printf("\nPlease Enter the First Array Elements\n");
 for(i = 0; i < Size; i++)
  {
      scanf("%d", &a[i]);
  }
   
 printf("\nPlease Enter the Second Array Elements\n");
 for(i = 0; i < Size; i ++)
  {
      scanf("%d", &b[i]);
  }

 //Swapping two Arrays 
 for(i = 0; i < Size; i++)
  {
    a[i] = a[i] ^ b[i];
    b[i] = a[i] ^ b[i]; 
    a[i] = a[i] ^ b[i];
  }

 printf("\n a[%d] Array Elements After Swapping \n", Size); 
 for(i = 0; i < Size; i ++)
  {
      printf(" %d \t ",a[i]);
  }

printf("\n\n b[%d] Array Elements After Swapping \n", Size); 
 for(i = 0; i < Size; i ++)
  {
      printf(" %d \t ",b[i]);
  }

  return 0;
} 

OUTPUT

ANALYSIS

We are just explaining the logic for first variable only. Please refer Bitwise Operator in C to understand how bitwise operator work.

User Entered Values are a[0] = 8 and b[0] = 4. The binary values of 8 = 1000 and 4 = 0010.
a[0] = a[0] ^ b[0]
a[0] = 1000 ^ 0010
a[0] = 1010

b[0] = a[0] ^ b[0]
b[0] = 1010 ^ 0010
b[0] = 1000

a[0] = a[0] ^ b[0];
a[0] = 1010 ^ 1000
a[0] = 0010
Final Values after swapping two arrays: a[0] = 4 and b[0] = 8

Do the same for remaining values a[1], a[2], a[3] and b[1], b[2], b[3]

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