Data Structures using C

Introduction to Arrays

An array stores a collection of similar elements under a single variable name. Each element is accessed using an index, and indexing starts from 0 in C.

• Stores multiple values using one variable
• Elements occupy contiguous memory locations
• Allows direct access through indexes

Declaration and Initialization

Arrays are declared using a data type, array name and size.

int numbers[5];

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

Common Array Operations

Arrays support several common operations used to manipulate and process elements.

Accessing Elements

Individual elements are accessed using indexes.

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

printf("%d",arr[2]);

Time Complexity: O(1)

Traversal

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

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

Time Complexity: O(n)

Searching

Searching is used to find a specific element in an array.

int key=30;

for(int i=0;i<5;i++){
   if(arr[i]==key)
      printf("Found");
}

Time Complexity: O(n)

Insertion

Insertion adds a new element at a specific position by shifting elements.

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

arr[pos]=value;

Time Complexity: O(n)

Deletion

Deletion removes an element and shifts remaining elements.

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

Time Complexity: O(n)

Updating Elements

Updating changes an existing value using its index.

arr[1]=100;

Time Complexity: O(1)

Applications of Arrays

• Searching algorithms
• Sorting algorithms
• Matrix representation
• Implementation of stacks and queues

Advantages of Arrays

• Fast access using indexes
• Easy traversal of elements
• Efficient memory usage for fixed-size data

Limitations of Arrays

• Fixed size once declared
• Insertion and deletion operations are costly
• Stores only same data type elements