Question

Having issues using binary search on a pointer array.

1. Write 1000 random ints to file

2. Binary Search to find if number exists in element from file.

int main()

{

ArrayActions action;  

int count;

int userInput;

int num = 1000;

int array[num];

ofstream myFile ("/Users/chan/Desktop/LANEY_CIS27/Assignemtn2_CIS27/Assignemtn2_CIS27/File.txt");  

//Set srand with time to generate unique random numbers

srand((unsigned)time(0));  

//Format random num up to 999

for(count = 0; count < num; count++)

{

array[count] = rand() % 1000;

}

  

  

  

//Condition to check if file is open

if (myFile.is_open())

{

for (int i = 0 ; i < num; i++)

{

//Write all random values to myFile

action.bubblesort(array, num);

myFile << array[i] << "\n";

}

  

cout << "------Ouput is written to myFile--------\n";

  

  

//Close File

myFile.close();

  

}

else

cout<<"File doesn't exist.\n";

cout << "Enter input from menu: ";

cin >> userInput;

  

//int n = sizeof(array) / sizeof(array[0]);

int result = action.binarySearch(array, 0, num-1, userInput);

if (result == -1)

cout << "Element is not present in array\n";

else

cout << "Element is present at index " << result << endl;

int binarySearch(int *arr, int l, int r, int x)

{

while (l <= r) {

int m = l + (r - l) / 2;

  

// Check if x is present at mid

if (arr[m] == x)

return m;

  

// If x greater, ignore left half

if (arr[m] < x)

l = m + 1;

  

// If x is smaller, ignore right half

else

r = m - 1;

}

  

// if we reach here, then element was

// not present

return -1;

}

  

Answer 1

Code:

#include<iostream>
#include <fstream>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
class ArrayActions
{
   public:

int binarySearch(int *arr, int l, int r, int x)
{
while (l <= r) {
int m = l + (r - l) / 2;
// Check if x is present at mid
if (arr[m] == x)
return m;
// If x greater, ignore left half
if (arr[m] < x)
l = m + 1;
// If x is smaller, ignore right half
else
r = m - 1;
}
// if we reach here, then element was
// not present
return -1;
}
void bubblesort(int *a,int num)
{
   int i, j,temp;
   for(i = 0; i<num; i++) {
        for(j = i+1; j<num; j++){
       if(a[j] < a[i]) {
        temp = a[i];
        a[i] = a[j];
        a[j] = temp;
           }
            }
       }
   }
};
int main ()
{
ArrayActions action;
int count;

int userInput;

int num = 1000;

int array[num];

ofstream myFile ("D:/File.txt");

//Set srand with time to generate unique random numbers

srand((unsigned)time(0));

//Format random num up to 999

for(count = 0; count < num; count++)
{
array[count] = rand() % 1000
}

//Condition to check if file is open

if (myFile.is_open())

{

for (int i = 0 ; i < num; i++)

{

//Write all random values to myFile

action.bubblesort(array, num);

myFile << array[i] << "\n";

}

cout << "------Ouput is written to myFile--------\n";

//Close File

myFile.close();

}

else

cout<<"File doesn't exist.\n";

cout << "Enter input from menu: ";

cin >> userInput;

//int n = sizeof(array) / sizeof(array[0]);

int result = action.binarySearch(array, 0, num-1, userInput);

if (result == -1)

cout << "Element is not present in array\n";

else

cout << "Element is present at index " << result << endl;
}

Output: