Arrays

It is a data structure to store multiple variables

• same type
• contiguous in memory
• linear
• index starts from zero (0)

Syntax

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

Pass by Reference

it will access by address

void changeArr(int arr[],int size){
	for(int i=0;i<size;i++){
		arr[i]=2*arr[i];
		
int main(){		
	int arr[]={1,2,3};
	changeArr(arr,3);
	for(int i=0;i<3;i++){
		cout<<arr[i]<<endl;  //value will change in the main function
		                     //this is because of reference value

Linear Search Algorithm

it is a search operation to find a target value in an array .use a loop and check every element one by one until you find the target value

for(int i=0;i<size;i++){
	if(arr[i]==target){
		return i;
	}
}
return -1;

Time Complexity=O(n)

2 Pointer Approach Algorithm

start and end pointer picked and swap .then increase of start value and decrease of end value and swap and repeat the process until start ≤ end

int st=0;
int en=size-1;
while(st<en){
	swap(arr[st],arr[en]);
	st++;
	en--;
}

Time Complexity=O(n)