Linear Search

#include<stdio.h>

main()
{

    int arr[10],i,n,key,c=0;

    printf("Enter the size of an array: ");
    scanf("%d",&n);

    printf("Enter the elements of the array: ");
    for(i=0;i<=n-1;i++)
 {
         scanf("%d",&arr[i]);
    }

    printf("Enter the number to be search: ");
    scanf("%d",&key);
    
 for(i=0;i<=n-1;i++)
 {
         if(arr[i]==key)
   {
             c=1;
             break;
         }
    }
    if(c==0)
         printf("The number is not found");
    else
         printf("The number is found");

    return 0;
}

Binary search

#include<stdio.h>

main()
{

    int arr[100],i,n,key,c=0,first,last,mid;

    printf("Enter the number of element in array :   ");
    scanf("%d",&n);

    printf("Enter the elements in ascending order :   ");
    for(i=0;i<n;i++)
 {
         scanf("%d",&arr[i]);
    }

    printf("Enter the number to be search :   ");
    scanf("%d",&key);

    first=0;
 last=n-1;
    
    while(first<=last)
 {
         mid=(first+last)/2;
         
         if(key==arr[mid])
   {
             c=1;
             break;
         }
         else if(key<arr[mid]){
             last=mid-1;
         }
         else
             first=mid+1;
    }
    if(c==0)
         printf("The number is not found.");
    else
         printf("The number is found.");

    return 0;
}

Binary search ( Recursion )

#include<stdio.h>

int binary(int [],int,int,int,int);

main()
{
 int a[50],i,n,m,first,last,c;
 
 printf("enter the number of elements\n");
 scanf("%d",&n);
 
 printf("enter all elements\n");
 for(i=0;i<n;i++)
 scanf("%d",&a[i]);
 
 printf("enter the number to be searched\n");
 scanf("%d",&m);
 
 first=0;
 last=n-1;
 
 c=binary(a,n,m,first,last);
 
 if(c==0)
 printf("element NOT FOUND\n");
 else
 printf("element found\n");
}

int binary(int a[],int n,int m, int first, int last)
{
 int mid,c=0;
 
 if(first<=last)
 {
   mid=(first+last)/2;
   
   if(m==a[mid])
   {
    c=1;
      }
   else
   {
    if(m<a[mid])
    return binary(a,n,m,first,mid-1);
    else
    return binary(a,n,m,mid+1,last); 
   }
}
 return c;
}