Linear Search

Linear search is a very simple search algorithm. In this type of search, a sequential search is made over all items one by one. Every item is checked and if a match is found then that particular item is returned, otherwise the search continues till the end of the data collection.

How Linear Search works

Algorithm

Step 1 −Set i to 1
Step 2 − if i > n then go to step 7
Step 3 − if A[i] = x then go to step 6
Step 4 − Set i to i + 1
Step 5 − Go to Step 2
Step 6 − Print Element x Found at index i and go to step 8
Step 7 − Print element not found
Step 8 − Exit

#include <stdio.h>

            #define MAX 20
            
            // array of items on which linear search will be conducted.
            int intArray[MAX] = {1,2,3,4,6,7,9,11,12,14,15,16,17,19,33,34,43,45,55,66};
            
            void printline(int count) {
               int i;
                
               for(i = 0;i <count-1;i++) {
                  printf("=");
               }
                
               printf("=\n");
            }
            
            // this method makes a linear search. 
            int find(int data) {
            
               int comparisons = 0;
               int index = -1;
               int i;
            
               // navigate through all items 
               for(i = 0;i<MAX;i++) {
                
                  // count the comparisons made 
                  comparisons++;
                    
                  // if data found, break the loop
                  if(data == intArray[i]) {
                     index = i;
                     break;
                  }
               }   
                
               printf("Total comparisons made: %d", comparisons);
               return index;
            }
            
            void display() {
               int i;
               printf("[");
                
               // navigate through all items 
               for(i = 0;i<MAX;i++) {
                  printf("%d ",intArray[i]);
               }
                
               printf("]\n");
            }
            
            void main() {
               printf("Input Array: ");
               display();
               printline(50);
                
               //find location of 1
               int location = find(55);
            
               // if element was found 
               if(location != -1)
                  printf("\nElement found at location: %d" ,(location+1));
               else
                  printf("Element not found.");
            }

If we compile and run the above program, it will produce the following result −

Output

Input Array: [1 2 3 4 6 7 9 11 12 14 15 16 17 19 33 34 43 45 55 66 ]
        ==================================================
        Total comparisons made: 19
        Element found at location: 19