Linear Search

  Problem Statement :  write a C program with function to search a given element say key in arr[].

Logic:

Input : arr[]={10,20,30,40,25,35,45,55,60,65}

key=25

Output: 5

Element is found at 5 position

Input : arr[]={10,20,30,40,25,35,45,55,60,65}

key=26

Output: -1

Element not  found

Time complexity -  O(n)

A simple Algorithm for  linear search, 

1.  Start from the lower element of arr[] i.e arr[0] and one by one compare key with each element of arr[] till end of array.

2.  If key matches with an element, return the index.

3.  If key doesn’t match with any of elements, return -1

C Code for Linear Search using function:

#include<stdio.h>

int search(int arr[], int n, int key) ;//Function Prototype

int main()

{

int i,n,key,arr[10]; // declaration part

printf("\n Enter size of array:");

scanf("%d",&n);

printf("\n Enter element of array:");

for(i=0;i<n;i++)   // Scan array of size n

{

    scanf("%d",&arr[i]);

   

}

printf("\n Entered array is:");

for(i=0;i<n;i++)   // Print array

{

    printf("\"%d\"\t",arr[i]);

   

}

printf("\n Enter key to find in aray:");

scanf("%d",&key);   //scan key for finding

i=search(arr,n,key); //call  search function and assign return value to i

if(i==-1)    //now check return value if -1 then no element found

printf("\n Key not found in array");

else        //else show element position in array

printf("\n Key found in array at position %d",i);

return 0;

getchar();

}

int search(int arr[], int n, int key) //search function

{

    int i;

    for (i = 0; i < n; i++)  //check for key matching linearly one by one element

        if (arr[i] == key)  // Condition for cheching equity of key and array element

         return i+1;

    return -1;

}

/*

Output

Enter size of array:10

Enter element of array:10 20 30 40 50 60 70 80 90 100

Entered array is:"10" "20" "30" "40" "50" "60" "70" "80" "90" "100"

Enter key to find in array:80

Enter Key found in array at position 8

*/

See Also :Linear Search with Pointer