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Last Post by vmanes
0

Look at the order you are using the search functions.
You call the function, looking for a fixed number.
You then ask the user to enter a search value.
You then test the result of your search, for that fixed number, which is not the user's input (most of the time, anyway.)

How about:
Ask user for number.
Call the function, using that input variable as the search key
Then evaluate the result from the function and display found/not found message.

0

I updated the codes but still it doesnt do binary search!!!! why?/ can any one find out what i am doing wrong here

/* Linear and Binary search


*/

#include <iostream>

using namespace std;

// Function prototype

int searchList(int [], int , int );

int binarySearch(int [], int, int);

 const int size = 20;

int main()

{
int tests[20]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};

 int num1, num2;
 
int result1, result2;

//search the array for 19




// if searchList  returns -1 , then num1 is not found
cout << "Enter the number you wish to search for: ";
cin >> num1;

result1 = searchList(tests, size ,num1);
   if (result1 == -1)
   {
       cout<<"There is no "<<num1<< "Enter again"<<endl;
       cin>>num1;
   }
   
   else 
   {
       cout << "your number is found"<<endl;
       cout <<"and its position is =";
       cout<< (result1+1)<<endl; 
       
   }
    // calling II Function for Binary search
    
result2 = binarySearch(tests , size, num2);
    
cout << "Enter the number you wish to search for: ";
cin >> num2;
result2 = binarySearch(tests , size, num2);
       if (result2 == -1)
       cout << "That number does not exist in the array.\n";
       else
       {
           cout << "That ID is found at element " << result2;
                cout << " in the array.\n"; 
                } 
   
   
system("PAUSE");
    return 0;
}

/*
**************************************

 void displayList( int [], int)

 {
 
 
 }

/**********************************************************/

/*SearchList Function performs a linear search. Array  name is list 
and it has a max numElem elements . 
if the number  is found 
If the number is found, its array 
subscript is returned. Otherwise, -1 is returned. *
****************************************************************
*/

int searchList(int list [], int numElem, int value)

{
    int index =0 ;
    int position = -1;
    bool found = false;
    
    while (index < numElem && !found)  
    
    {
        if (list [index]== value )  
        {
                found = true ;
                 position= index;
        }  
          index++;
    }

return position;
    
}

//********************************************************************
/* The function should keep a count of the
number of comparisons it makes until it finds the value. The*/



//***********************************************************************
/* Binary search*/

int binarySearch(int array[], int numElems, int value)
{
    int first = 0,           // First array element
        last = numElems - 1,    // Last array element
        middle,        // Midpoint of search
        position = -1; // Position of search value
        bool found = false;     // Flag

while (!found && first <= last)
{
	middle = (first + last) / 2; // Calculate midpoint
}	
	if (array[middle] == value) // If value is found at midpoint
		{
	    found = true;
	    position = middle;
		}
  else if (array[middle] > value) // If value is in lower half
	{
		last = middle - 1;
    }
 else
    {
    first = middle + 1;        // If value is in upper half
      }
return position;
}
0

Proper indenting would help you find the error.

while (!found && first <= last)
	{
		middle = (first + last) / 2; // Calculate midpoint
	}	
	if (array[middle] == value) // If value is found at midpoint
	{
		found = true;
		position = middle;
	}
	else if (array[middle] > value) // If value is in lower half
	{
		last = middle - 1;
	}
	else
	{
		first = middle + 1;        // If value is in upper half
	}

Can you see it now?

0

Proper indenting would help you find the error.

while (!found && first <= last)
	{
		middle = (first + last) / 2; // Calculate midpoint
	}	
	if (array[middle] == value) // If value is found at midpoint
	{
		found = true;
		position = middle;
	}
	else if (array[middle] > value) // If value is in lower half
	{
		last = middle - 1;
	}
	else
	{
		first = middle + 1;        // If value is in upper half
	}

Can you see it now?

Ok i caught the error

Edited by rafta: n/a

0

Now How Can i find how many pass both searches are making.

Put a counter in the loop. Display the results before the function returns, or pass it back as reference parameter.

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