Searching in singly linked list

The process of finding the location of a particular element in a list is called searching. To search an element in a list, we need to traverse through the list. After which, we will make the comparison of every element of the list with the specified element. The location of the element is returned from the function, in case an element is matched with any of the list’s elements.

Algorithm:

Step 1: SET PTR = HEAD
Step 2: Set I = 0
STEP 3: IF PTR = NULL
WRITE “EMPTY LIST”
GOTO STEP 8
END OF IF
STEP 4: REPEAT STEP 5 TO 7 UNTIL PTR != NULL
STEP 5:IF ptr → data = item
WRITE i+1
End of IF
STEP 6: I = I + 1
STEP 7:PTR = PTR → NEXT
[END OF LOOP]
STEP 8: EXIT

Example in C:

#include<stdio.h>  
#include<stdlib.h>  
void createNode(int);  
void search();  
struct node  
{  
    int data;  
    struct node *next;  
};  
struct node *head;  
void main ()  
{  
    int choice,item,loc;  
    do   
    {  
        printf("\n1.Insert Node\n2.Search\n3.Exit\n4.Enter your choice:\n");  
        scanf("%d",&choice);  
        switch(choice)  
        {  
            case 1:  
            printf("\nEnter the element to insert:\n");  
            scanf("%d",&item);  
            createNode(item);  
            break;   
            case 2:  
            search();  
            case 3:  
            exit(0);  
            break;    
            default:  
            printf("\nPlease enter a valid choice.\n");  
        }  
 
    }while(choice != 3);  
}  
    void createNode(int item)  
    {  
        struct node *ptr = (struct node *)malloc(sizeof(struct node *));  
        if(ptr == NULL)  
        {  
            printf("\nOVERFLOW\n");  
        }  
        else  
        {  
            ptr->data = item;  
            ptr->next = head;  
            head = ptr;  
            printf("\nNode inserted successfully!!\n");  
        }  
 
    }  
void search()  
{  
    struct node *ptr;  
    int item,i=0,flag;  
    ptr = head;   
    if(ptr == NULL)  
    {  
        printf("\nThe list is Empty.\n");  
    }  
    else  
    {   
        printf("\nEnter the element to search:\n");   
        scanf("%d",&item);  
        while (ptr!=NULL)  
        {  
            if(ptr->data == item)  
            {  
                printf("Element found at location %d ",i+1);  
                flag=0;  
            }   
            else  
            {  
                flag=1;  
            }  
            i++;  
            ptr = ptr -> next;  
        }  
    }     
 
}

Output:

1.Insert Node 
2.Search 
3.Exit 
4.Enter your choice: 
1 
 
Enter the element to insert: 
2 
 
Node inserted successfully!! 
 
1.Insert Node 
2.Search 
3.Exit 
4.Enter your choice: 
1 
 
Enter the element to insert: 
4 
 
Node inserted successfully!! 
 
1.Insert Node 
2.Search 
3.Exit 
4.Enter your choice: 
1 
 
Enter the element to insert: 
5 
 
Node inserted successfully!! 
 
1.Insert Node 
2.Search 
3.Exit 
4.Enter your choice: 
1 
 
Enter the element to insert: 
6 
 
Node inserted successfully!! 
 
1.Insert Node 
2.Search 
3.Exit 
4.Enter your choice: 
1 
 
Enter the element to insert: 
7 
 
Node inserted successfully!! 
 
1.Insert Node 
2.Search 
3.Exit 
4.Enter your choice: 
1 
 
Enter the element to insert: 
8 
 
Node inserted successfully!! 
 
1.Insert Node 
2.Search 
3.Exit 
4.Enter your choice: 
2 
 
Enter the element to search: 
5 
Element found at location 4