Why is the line 12 is printed twice? - c

Question

Given Problem
Implement the binary search algorithm in a non-recursive manner.
Keep the search array as a numeric array, initialized at time of declaration and keep it global.
The program should ask for a value to search, and then tell the location where it is found.
If the value is not found the program should display not found.
* Additionally the program should display the total number of comparisons done to locate the value ( or realize that the value was not found)
My Solution
#include<stdio.h>
int arr[]={1,3,4,6,8,9,10,15,17,21};
int bi_search(int n)
{
int start=0,end=9,mid=0,count=0;
while(start<=end)
{
count++;
mid=(start+end)/2;
if(n==arr[mid])
{
printf("\nThe total number of comparisons done to locate the value--%d\n",count);
return mid;
}
else if(n<arr[mid])
end=mid-1;
else
start=mid+1;
}
printf("\nThe total number of comparisons done to realize that the value was not found--%d\n",count);
return-1;
}
main()
{
int n=0,ch=0;
do
{
printf("\nEnter the value you want to search for--\n");
scanf("%d",&n);
if(bi_search(n)==-1)
printf("\nSORRY :( !! \nThe value was not found.");
else
printf("\nHurray :) !! \nThe value you entered found at %d position", bi_search(n)+1);
printf("\nEnter:-\n\t1 to continue.\n\t2 to terminate.\n");
scanf("%d",&ch);
}while(ch==1);
printf("\nThank You\n");
return 0;
}
When I run this code, in function bi_search(int n) whenever arr[mid] becomes equal to n, line The total number of comparisons done to locate the value-- is getting printed twice.

Answer 1

You are calling the bi_search function twice. Once in your if statement, and again in a printf statement. You should call it only once, and cache the value.
main()
{
int n=0,ch=0;
do
{
printf("\nEnter the value you want to search for--\n");
scanf("%d",&n);
if(bi_search(n)==-1) // Calling it here
printf("\nSORRY :( !! \nThe value was not found.");
else
printf("\nHurray :) !! \nThe value you entered found at %d position", bi_search(n)+1); // And here
printf("\nEnter:-\n\t1 to continue.\n\t2 to terminate.\n");
scanf("%d",&ch);
}while(ch==1);
printf("\nThank You\n");
return 0;
}

Answer 2

It is just because you are calling binary search function twice.
One on if part and other on else if part.
Alternatively you can do the same in following way
int temp = bi_search(n);
if (temp == -1)
printf("Value not found\n");
else
printf("Value found at position %d\n", temp);

Answer 3

Your main routine can look like this:
int main()
{
int n = 0, ch = 0;
do
{
printf("\nEnter the value you want to search for--\n");
scanf("%d", &n);
int res = bi_search(n); // store the result
if (res == -1) // check if not find
printf("\nSORRY :( !! \nThe value was not found.");
else
printf("\nHurray :) !! \nThe value you entered found at %d position", res + 1); // print if find
printf("\nEnter:-\n\t1 to continue.\n\t2 to terminate.\n");
scanf("%d", &ch);
} while (ch == 1);
printf("\nThank You\n");
return 0;
}
1) int main() (to make compiler calm)
2) int res = bi_search(n) (to avoid second bi_search() call)