Linear search c program

Linear search c program

#include <stdio.h>

int main()

{

   int array[100], search, c, number;

   printf("Enter the number of elements in array\n");

   scanf("%d",&number);

   printf("Enter %d numbers\n", number);

   for ( c = 0 ; c < number ; c++ )

      scanf("%d",&array[c]);

   printf("Enter the number to search\n");

   scanf("%d",&search);

   for ( c = 0 ; c < number ; c++ )

   {

      if ( array[c] == search )     /* if required element found */

      {

         printf("%d is present at location %d.\n", search, c+1);

         break;

      }

   }

   if ( c == number )

      printf("%d is not present in array.\n", search);     

   return 0;

}

Output of program:

Enter the number of elements in array

5

Enter  5  numbers

6

5

4

9

2

1

Enter the number to search

6

6 is present at location 1

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;

}

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).

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