C Exercises: Rotate an array by N positions

Last update on March 18 2025 13:21:23 (UTC/GMT +8 hours)

39. Rotate Array by N Positions

Write a program in C to rotate an array by N positions.
Note: The size of first array is (m+n) but only first m locations are populated remaining are empty. The second array is of size equal to n.

This problem involves rotating the elements of an array to the left by N positions. The output shows the elements that come after the Nth position, the elements before it, and then the final rotated array where the elements after the Nth position are moved to the beginning of the array, followed by the initial elements up to the Nth position.

Visual Presentation:

C Exercises: Rotate an array by N positions

Sample Solution:

C Code:

#include <stdio.h>

// Function to shift the elements of an array by one position to the left
void shiftArr1Pos(int *arr1, int arrSize) {
    int i, temp;
    temp = arr1[0];  // Store the first element temporarily

    // Shift elements to the left by one position
    for (i = 0; i < arrSize - 1; i++) {
        arr1[i] = arr1[i + 1];
    }
    arr1[i] = temp;  // Place the first element at the end
}

// Function to rotate an array by 'rotFrom' positions
void arr1Rotate(int *arr1, int arrSize, int rotFrom) {
    int i;

    // Perform rotation 'rotFrom' times
    for (i = 0; i < rotFrom; i++) {
        shiftArr1Pos(arr1, arrSize);  // Rotate the array by one position
    }
    return;
}

// Main function
int main() {
    int arr1[] = {0, 3, 6, 9, 12, 14, 18, 20, 22, 25, 27}; 
    int ctr = sizeof(arr1) / sizeof(arr1[0]);
    int i;

    // Print original array
    printf("The given array is :  ");
    for (i = 0; i < ctr; i++) {
        printf("%d  ", arr1[i]);
    } 
    printf("\n");

    // Print values from 4th position
    printf("From 4th position, the values of the array are :  ");
    for (i = 4; i < ctr; i++) {
        printf("%d  ", arr1[i]);
    } 
    printf("\n"); 

    // Print values before 4th position
    printf("Before 4th position, the values of the array are :  ");
    for (i = 0; i < 4; i++) {
        printf("%d  ", arr1[i]);
    } 
    printf("\n");     

    // Rotate the array from the 4th position
    arr1Rotate(arr1, ctr, 4);
    printf("\nAfter rotating from the 4th position, the array is: \n");
    for (i = 0; i < ctr; i++) {
        printf("%d ", arr1[i]);
    }
    return 0;
}

Sample Output:

The given array is :  0  3  6  9  12  14  18  20  22  25  27  
From 4th position the values of the array are :  12  14  18  20  22  25  27  
Before 4th position the values of the array are :  0  3  6  9  

After rotating from 4th position the array is: 
12 14 18 20 22 25 27 0 3 6 9

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to rotate an array left by N positions using reversal algorithm.
Write a C program to rotate an array right by N positions using cyclic replacements.
Write a C program to rotate an array by N positions and then print the array in two halves separately.
Write a C program to rotate an array by N positions using recursion.

C Programming Code Editor:

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