# C Program to accept an array & swap elements using pointers

For a better understanding, we always recommend you to learn the basic topics of C programming listed below:

In this c program, we have to accept an array of elements and swap the elements at the third position with the element of the fourth position using a pointer. Before going into the program, we have to know more about pointers and how this swapping of elements in an array can be executed using pointers.

## What is a pointer?

A pointer is simply a variable whose value is the address of another variable. Also, we have to know how we use a Pointer in a program. The steps are.

1. Define a pointer variable
2. Assign the address of the variable to a Pointer
3. Access the value at the address available in the Pointer variable

Given below steps are used in the program to perform Swapping of elements

• Initially declare the Array and define all the elements one by one.
• Make a function with two pointer variables(i.e., third and fourth).
• Inside this Function creates a temporary variable first, then this variable is assigned the value at the third pointer.
• Now the value at the third pointer swaps the value to the fourth pointer.
• Then value at the fourth pointer changes to the value of the temporary variable.

In this way, we perform swapping in this C program.

### ALGORITHM

STEP 1: Include the header files to use the built-in functions in the C program.

STEP 2: Declare the Array x[10] as float and i, n as an integer.

STEP 3: Define the function swap34(float *ptr1, float *ptr2).

STEP 4: Read the number of elements into the variable n.

STEP 5: Read the elements of the Array into the array x+i using `for loop`.

STEP 6: Call the Function swap34(x+2,x+3) to interchange the 3rd element by 4th.

STEP 7: Display the resultant Array as x[i] using `for loop`.

Function void swap34(float *ptr1,float *ptr2)

STEP 1: Declare the variable temp as the float.

STEP 2: Assign temp=*ptr1.

STEP 3: *ptr1=*ptr2.

STEP 4: *ptr2=temp

## C Source Code

```                                          ```#include <stdio.h>

void main() {
float x[10];
int i, n;
void swap34(float * ptr1, float * ptr2); /* Function Declaration */
printf("How many Elements...\n");
scanf("%d", & n);
printf("Enter Elements one by one\n");
for (i = 0; i < n; i++) {
scanf("%f", x + i);
}
swap34(x + 2, x + 3); /* Function call:Interchanging 3rd element by 4th */
printf("\nResultant Array...\n");
for (i = 0; i < n; i++) {
printf("X[%d] = %f\n", i, x[i]);
}
} /* End of main() */

/* Function to swap the 3rd element with the 4th element in the array */

void swap34(float * ptr1, float * ptr2) /* Function Definition */ {
float temp;
temp = * ptr1;
* ptr1 = * ptr2;
* ptr2 = temp;
}```
```

## OUTPUT

```How many Elements...
10

Enter Elements one by one
10
20
30
40
50
60
70
80
90
100

Resultant Array...

X[0] = 10.000000
X[1] = 20.000000
X[2] = 40.000000
X[3] = 30.000000
X[4] = 50.000000
X[5] = 60.000000
X[6] = 70.000000
X[7] = 80.000000
X[8] = 90.000000
X[9] = 100.000000```
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