Common Array Operations in C

1. Traversing an Array

Traversing means visiting each element of the array one by one.

#include <stdio.h>

int main() {

    int a[5] = {10,20,30,40,50};

    for(int i = 0; i < 5; i++){
        printf("%d ", a[i]);
    }

    return 0;
}

2. Searching an Element (Linear Search)

Linear search checks elements one by one until the key is found.

#include <stdio.h>

int main() {

    int a[6] = {12, 45, 7, 22, 9, 30};
    int key = 22, found = 0;

    for(int i = 0; i < 6; i++){
        if(a[i] == key){
            found = 1;
            break;
        }
    }

    if(found)
        printf("Element found");
    else
        printf("Not found");

    return 0;
}

3. Updating an Element

Updating means changing an existing value using its index.

#include <stdio.h>

int main() {

    int a[4] = {5,10,15,20};

    a[2] = 100;

    for(int i = 0; i < 4; i++){
        printf("%d ", a[i]);
    }

    return 0;
}

4. Inserting an Element (At Any Position)

Insertion shifts elements to the right to make space.

#include <stdio.h>

int main() {

    int a[10] = {2,4,6,8,10};
    int n = 5;
    int pos = 2;
    int value = 99;

    for(int i = n; i > pos; i--){
        a[i] = a[i - 1];
    }

    a[pos] = value;
    n++;

    for(int i = 0; i < n; i++){
        printf("%d ", a[i]);
    }

    return 0;
}

5. Deleting an Element

#include <stdio.h>

int main() {

    int a[6] = {10,20,30,40,50,60};
    int pos = 2;

    for(int i = pos; i < 6-1; i++){
        a[i] = a[i+1];
    }

    for(int i = 0; i < 5; i++){
        printf("%d ", a[i]);
    }

    return 0;
}

6. Reversing the Array

#include <stdio.h>

int main() {

    int a[5] = {1,2,3,4,5};

    for(int i = 4; i >= 0; i--){
        printf("%d ", a[i]);
    }

    return 0;
}

7. Sorting (Ascending Order)

#include <stdio.h>

int main() {

    int a[6] = {5,2,9,1,7,3};
    int temp;

    for(int i = 0; i < 6; i++){
        for(int j = i+1; j < 6; j++){
            if(a[j] < a[i]){
                temp = a[i];
                a[i] = a[j];
                a[j] = temp;
            }
        }
    }

    for(int i = 0; i < 6; i++){
        printf("%d ", a[i]);
    }

    return 0;
}

8. Sorting (Descending Order)

#include <stdio.h>

int main() {

    int arr[5] = {4,1,8,2,7};
    int temp;

    for(int i = 0; i < 5; i++){
        for(int j = i+1; j < 5; j++){
            if(arr[j] > arr[i]){
                temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
    }

    for(int i = 0; i < 5; i++){
        printf("%d ", arr[i]);
    }

    return 0;
}

9. Merging Two Arrays

#include <stdio.h>

int main() {

    int a[3] = {1,2,3};
    int b[3] = {4,5,6};
    int c[6];

    for(int i = 0; i < 3; i++){
        c[i] = a[i];
    }

    for(int i = 0; i < 3; i++){
        c[i+3] = b[i];
    }

    for(int i = 0; i < 6; i++){
        printf("%d ", c[i]);
    }

    return 0;
}

10. Counting Even and Odd in Array

#include <stdio.h>

int main() {

    int arr[7] = {11,20,33,40,55,60,71};
    int even = 0, odd = 0;

    for(int i = 0; i < 7; i++){
        if(arr[i] % 2 == 0)
            even++;
        else
            odd++;
    }

    printf("Even = %d\nOdd = %d", even, odd);

    return 0;
}

Practice Questions

1. Insert a number in the array at a given position.
2. Delete a number from a given index.
3. Sort an array using Bubble Sort.
4. Search an element using Linear Search.
5. Merge two sorted arrays.

Practice Task