DS – Arrays in C – Ameerpet Technologies

Primitive type:

Variables are used to store data.
Primitive variable can store only one value at a time.
For example,

int main(){
            int a=5;
            a=10;
            a=20;
            printf(“a val : %d \n”, a);   // prints – 20
            return 0;
}

Array:

Array is used to store more than one value but of same type.
For example, storing 100 students’ average marks.

Array creation:

In array variable declaration, we need to specify the size
Array variable stores base address of memory block.
Array elements store in consecutive memory location.

Process Array elements:

Array memory locations must be accessed through their index.
Index values starts from 0 to Size-1

How to access array elements?

Array consists multiple values.
We can simply use loops to process array locations.

Reading	Printing
int i; for(i=0 ; i<5 ; i++) { scanf(“%d”, &marks[i]); }	int i; for(i=0 ; i<5 ; i++) { printf(“%d”, marks[i]); }

Length of array:

sizeof() function returns the total size of array.
We can find the length of array by dividing total size with single element size.

int main()
{
            float arr[5];
            printf(“Total size of array : %d \n”, sizeof(arr));
            printf(“Array element size : %d \n”, sizeof(arr[0]));
            printf(“Length of Array : %d \n”, sizeof(arr)/sizeof(arr[0]));
return 0;
}

C program to read elements into array and display:

int main ()
{
            int arr[5], i;
            printf(“Enter 5 elements : \n”);
            for(i=0 ; i<5 ; i++){
                        scanf(“%d”, &arr[i]);
            }
            printf(“Array elements are : \n”);
            for(i=0 ; i<5 ; i++){
                        printf(“%d \n”, arr[i]);
            }
            return 0;
}

C Program to find sum of array elements:

int main ()
{
            int arr[5] = {10, 20, 30, 40, 50}, i, sum=0;
            for(i=0 ; i<5 ; i++){
                        sum = sum + arr[i];
            }
            printf(“Sum of Array elements : %d \n”, sum);
            return 0;
}

C Program to display only even numbers in the array:

int main ()
{
            int arr[8] = {8, 5, 1, 7, 4, 3, 2, 9}, i;
            printf(“Even numbers of Array : \n”);
            for(i=0 ; i<8 ; i++){
                        if(arr[i]%2==0)
                                    printf(“%d \t”, arr[i]);
            }
            return 0;
}

C program to display the largest element in the array:

int main()
{
            int arr[8] = {7,2,9,14,3,27,5,4};
            int large=arr[0], i;
            for(i=1 ; i<8 ; i++){
                        if(arr[i]>large)
                                    large = arr[i];
            }
            printf(“Largest element is : %d \n”, large);
            return 0;
}

Pass Array as a parameter to a function:

We can pass array as input parameter to function.
By passing array name, the address will be passed as parameter.
We collect the address in Called Function by declaring same type array.

void display(int[]);
int main(){
            int a[5] = {10, 20, 30, 40, 50};
            display(a);
            return 0;
}
void display(int x[]){
            int i;
            printf(“Array is :\n”);
            for(i=0 ; i<5 ; i++){
                        printf(“%d\n”, x[i]);
            }
}

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