Linear search in c

Linear search c program

#include <stdio.h>
 
int main()
{
   int array[100], search, c, n;
 
   printf("Enter the number of elements in array\n");
   scanf("%d",&n);
 
   printf("Enter %d integer(s)\n", n);
 
   for (c = 0; c < n; c++)
      scanf("%d", &array[c]);
 
   printf("Enter the number to search\n");
   scanf("%d", &search);
 
   for (c = 0; c < n; c++)
   {
      if (array[c] == search)     /* if required element found */
      {
         printf("%d is present at location %d.\n", search, c+1);
         break;
      }
   }
   if (c == n)
      printf("%d is not present in array.\n", search);
 
   return 0;
}

Download Linear search program.

Output of program:

C program for binary search

Linear search for multiple occurrences

In the code below we will print all the locations at which required element is found and also the number of times it occur in the list.

#include <stdio.h>
 
int main()
{
   int array[100], search, c, n, count = 0;
 
   printf("Enter the number of elements in array\n");
   scanf("%d",&n);
 
   printf("Enter %d numbers\n", n);
 
   for ( c = 0 ; c < n ; c++ )
      scanf("%d",&array[c]);
 
   printf("Enter the number to search\n");
   scanf("%d",&search);
 
   for ( c = 0 ; c < n ; c++ )
   {
      if ( array[c] == search )    
      {
         printf("%d is present at location %d.\n", search, c+1);
  count++;
      }
   }
   if ( count == 0 )
      printf("%d is not present in array.\n", search);
   else
      printf("%d is present %d times in array.\n", search, count);
 
   return 0;
}

Download Linear search multiple occurrence program.

Output of code:

C program for linear search using function

#include <stdio.h>
 
int linear_search(int*, int, int);
 
int main()
{
   int array[100], search, c, n, position;
 
   printf("Enter the number of elements in array\n");
   scanf("%d",&n);
 
   printf("Enter %d numbers\n", n);
 
   for ( c = 0 ; c < n ; c++ )
      scanf("%d", &array[c]);
 
   printf("Enter the number to search\n");
   scanf("%d",&search);
 
   position = linear_search(array, n, search);
 
   if ( position == -1 )
      printf("%d is not present in array.\n", search);
   else
      printf("%d is present at location %d.\n", search, position+1);
 
   return 0;
} 
 
int linear_search(int *pointer, int n, int find)
{
   int c;
 
   for ( c = 0 ; c < n ; c++ )
   {
      if ( *(pointer+c) == find )
         return c;
   }
 
   return -1;
}

Time required to search an element using linear search algorithm depends on size of list. In best case element is present at beginning of list and in worst case element is present at the end. Time complexity of linear search is O(n).