Array

data_type name [size]

int array[10]
float array[5]

arr[0] -> accessing value using index

#include <stdio.h>

int main()
{
    int ar[5];
    ar[2] = 100;
    ar[3] = 102;
    ar[4] = 50;

    printf("%d", ar[2]);
    return 0;
}

• memory management of array

• input output of array

#include <stdio.h>

int main()
{
    int a[2];
    scanf("%d %d %d", &a[0], &a[1], &a[2]);
    printf("%d %d %d", a[0], a[1], a[2]);
    return 0;
}

• instead of hardcoded use loop

#include <stdio.h>

int main()
{
    int a[5];
    // scanf("%d %d %d", &a[0], &a[1], &a[2]);
    // printf("%d %d %d", a[0], a[1], a[2]);

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

    for (int i = 0; i <= 4; i++)
    {

        printf("%d ", a[i]);
    }

    return 0;
}

• reverse array

#include <stdio.h>

int main()
{
    int n;
    scanf("%d", &n);
    int a[n];

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

    for (int i = n-1 ; i >= 0; i--)
    {
        printf("%d ", a[i]);
    }


    return 0;
}

• initializing

#include <stdio.h>

int main()
{
    // int x = 10; // declare and initialize

    // int a[5]
    int a[5] = {10, 20, 23, 24, 25};

    //  not writting size is also ok in this case

    // int a[] = {10, 20, 23, 24, 25};

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

    return 0;
}

• in this case if we do not give all element only available value will be shown and empty spaces will be set 0;

• remember this will work only for fixed size array. if we take array size from the input it will not work

• sum of all values of array

#include<stdio.h>
int main ()
{
     int x;
     scanf("%d",&x);
     int arr[x];
     for(int i=0; i<x; i++){
        scanf("%d",&arr[i]);
     }

     int sum=0;
     for(int i=0; i<x; i++){
        printf("%d ",arr[i]);
        sum+=arr[i];
     }
      printf("\nsum=%d",sum);
    return 0;
   
}   

-absolute summation

#include <stdio.h>
#include <stdlib.h> // Required for abs()

int main() {
    int arr[] = {-5, 10, -3, 7, -2};
    int n = sizeof(arr) / sizeof(arr[0]);
    int absoluteSum = 0;

    for (int i = 0; i < n; i++) {
        absoluteSum += abs(arr[i]); // Convert to positive before adding
    }

    printf("The absolute sum is: %d\n", absoluteSum);
    // Output: 27 (5 + 10 + 3 + 7 + 2)
    return 0;
}