C++ Tutorial Index

C++ Tutorial C++ History C++ Installation C++ First Program C++ cin and cout C++ Data type C++ Variable C++ operator C++ Keywords

C++ Control Statements

C++ If C++ Nested if C++ If-else C++ If-else-if C++ Switch C++ Break C++ Continue C++ Goto C++ For loop C++ While loop C++ Do while loop

C++ Functions

C++ Call by Value C++ Call by Reference C++ Recursion Function C++ Inline function C++ Friend function

C++ Arrays

Single dimension array Two dimension array

C++ Strings

C++ Strings

C++ Inheritance

C++ Inheritance Single level Inheritance Multilevel Inheritance Multiple Inheritance Hierarchical Inheritance Hybrid Inheritance

C++ Polymorphism

C++ Polymorphism C++ Overloading C++ Overriding C++ Virtual Function

C++ Pointers

C++ Pointers C++ this pointer

C++ Exception Handling

C++ Exception Handling

C++ Constructors

C++ Constructors Default Constructor Parameterize Constructor Copy constructor Constructor Overloading Destructor

C++ File Handling

C++ File Handling C++ Writing to file C++ Reading file C++ Close file

Miscellaneous

C Vs C++ C++ Comments C++ Data Abstraction C++ Identifier C++ Memory Management C++ Storage Classes C++ Void Pointer C++ Array To Function C++ Expressions C++ Features C++ Interfaces C++ Encapsulation std::min in C++ External merge sort in C++ Remove duplicates from sorted array in C++ Precision of floating point numbers Using these functions floor(), ceil(), trunc(), round() and setprecision() in C++ C++ References C++ Friend Functions C++ Mutable keyword Unary Operators in C++ Initialize Array of objects with parameterized constructors in C++ Differences between #define & const in C/C++ C++ Program to Implement Shell Sort C++ Program to Implement Merge Sort Storage Classes in C Vector resize() in C++ Passing by Reference Vs. Passing by the pointer in C++ Free vs delete() in C++ goto statement in C and C++ C++ program to read string using cin.getline() C++ String Concatenation Heap Sort in C++ Swap numbers in C++ Input Iterators in C++ Fibonacci Series in C++ C ++ Program: Alphabet Triangle and Number Triangle C++ Program: Matrix Multiplication C++ Program to Print Fibonacci Triangle Stack in C++ Maps in C++ Queue in C++ C++ Bitset C++ Algorithms Priority Queue in C++ C++ Multimap C++ Deque Function Pointer in C++ Sizeof() Operators in C++ C++ array of Pointers free() Vs delete in C Timsort Implementation Using C++ CPP Templates C++ Aggregation C++ Enumeration C++ Math Functions C++ Object Class C++ Queue Initialize Vector in C++ Vector in C++ C++ STL Components Function overloading in C++ C++ Maximum Index Problem C++ find missing in the second array C++ Program to find the product array puzzle C++ Program To Find Largest Subarray With 0 Sum C++ Program To Move All Zeros To The End Of The Array C++ Program to find the element that occurs once C++ Program to find the largest number formed from an array Constructor Vs Destructor C++ Namespaces C++ OOPs Concept C++ Static C++ Structs C++ Try-Catch C++ User Defined Exceptions C++ Virtual Destructor C++ vs C# Malloc() and new in C++ Palindrome Number Program in C++ Snake Code in C++ Splitting a string in C++ Structure Vs Class in C++ Virtual Function Vs Pure Virtual Function C++ Bidirectional Iterators C++ Forward Iterators C++ Iterators C++ Output Iterators C++ Range-based For Loop Converting string into integer in C++ LCM Program in C++ Type conversion in C++ Add two numbers using the function in C++ Advantage and disadvantage friend function C++ Armstrong Number Program in C++ ATM machine program in C++ using functions Binary to Decimal in C++ Bit Manipulation in C++ C++ Constructor C++ Dijkstra Algorithm Using the Priority Queue C++ int into String C++ Signal Handling Decimal to Binary in C++ Decimal to Hexadecimal in C++ Decimal to Octal in C++ Factorial Program in C++ Function in C++ Hexadecimal to Decimal in C++ Octal to Decimal in C++ Reverse a Number in C++ Structure Vs Class in C++ C++ Forward Iterators C++ Output Iterators C++ Prime number program Char Array to String in C++ Constructor Overloading in C++ Default arguments in C++ Different Ways to Compare Strings in C++ Dynamic Binding in C++ Program to convert infix to postfix expression in C++ SET Data Structure in C++ Upcasting and Downcasting in C++ Reverse an Array in C++ Fast Input and Output in C++ Delete Operator in C++ Copy elision in C++ C++ Date and Time C++ Bitwise XOR Operator Array of sets in C++ Binary Operator Overloading in C++ Binary Search in C++ Implementing the sets without C++ STL containers Scope Resolution Operator in C++ Smart pointers in C++ Types of polymorphism in C++ Exception Handling in C++ vs Java Const Keyword in C++ Type Casting in C++ Static keyword in C++ vs Java Inheritance in C++ vs Java How to concatenate two strings in C++ Programs to Print Pyramid Patterns in C++ swap() function in C++ Structure of C++ Program Stringstream in C++ and its applications rand() and srand() in C / C++ C++ Ternary Operator C++ Scope of Variables While Loop Examples in C++ Star pattern in C++ using For Loops For Loop Examples in C++ Do-While Loop Examples in C++ Top 5 IDEs for C++ That You Should Try Once Assertions in C/C++ C++ Convert Int to String Continue in C++ While loop Diamond Pattern in C++ using For Loop How to Reverse a String in C++ using Do-While Loop How to Reverse a String in C++ using For Loop How to Reverse a String in C++ using While Loop Infinite loop in C++ Loops in C++ Returning Multiple Values from a Function using Tuple and Pair in C++ wcscpy(), wcslen(), wcscmp() Functions in C++ Auto keyword in C++ C++ 11 vs C++ 14 vs C++ 17 C++ STL (Standard Template Library) Differences Between C Structures and C++ Structures Divide by Zero Exception in C++ Dynamic Constructor in C++ Dynamic Memory Allocation in C++ Find the Size of Array in C/C++ without using sizeof() function Floating Point Operations and Associativity in C, C++ and Java Hello World Program in C++ How to create a table in C++ How to Setup Environment for C++ Programming on Mac Implementation of a Falling Matrix in C++ Message Passing in C++ Pointer to Object in C++ Templates in C++ vs Generics in Java Ways to Copy a Vector in C++ What does Buffer Flush mean in C++ sort() function in C++ Structure Sorting (By Multiple Rules) in C++ Similarities between C++ and Java std::distance in C++

Binary Search in C++

The binary search in the C++ programming language will be discussed. By continually halves the array and then seeking specified items from a half array; binary search is a technique for finding supplied elements from a sorted array. And so on until the perfect match is found. Only sorted data structures are supported. The binary search algorithm has an O time complexity (log n).

Algorithm

The algorithm for performing a binary search in C++ is as follows:

  • As a search key, start with the middle member of the whole array.
  • Return an index of the search key if the value of the search key is equal to the item.
  • Alternatively, if the search key's value is smaller than the item in the interval's middle, limit the interval to the bottom half.
  • Otherwise, limit it to the upper half of the page.
  • Check the value from the second point until the interval is empty or the value is discovered.
beg = 0 ;  
end = size - 1 ;  
while ( beg < = end )  
{  
// calculate mid value  
mid = ( beg + end ) / 2 ;  
/* if the specified element is found at mid index, terminate the process and return the index. */  
// Check middle element is equal to the defined element.  
If ( arr [ mid ] = = num )  
{  
return mid + 1 ;  
}  
else if ( arr [ mid ] > num )  
{  
    end = mid - 1 ;  
}  
else if ( arr [ mid ] < num )  
{  
    Beg = mid + 1 ;  
}  
}  
// If the element does not exist in the array, return -1.  
Return -1 ;

In C++ follow these steps to execute a binary search:

Step 1: Declare the variables and sort all of the items in an array (ascending or descending).

Step 2: Split the array element listings into halves.

Step 3: Now compare the target items to the array's centre member. Return the location of the middle element and finish the search if the target element's value matches that of the middle element.

Step 4: If the target element is less than the middle element, we look for it in the array's lower half.

Step 5: If the target element is larger than the centre element, we must look for it in the array's greater half.

Example 1: Using the binary search, locate the provided integer from a sorted array:

Let's use the C++ programming language to create a program that uses the binary search to discover a certain integer from a sorted array.

#include < iostream >  
#include < bits/stdc++.h >
#include < stdio >
#include < stdlib >
#include < conio.h >  
using namespace std ;  
int main ( )  
{  
    // declaration of the variables and array  
    int arr [ 100 ] , st , mid , end , i , num , tgt ;  
    cout << " Define the size of the array: " << endl ;  
    cin >> num ; // get size        
    // enter only sorted array  
        cout << " enter the values in sorted array either ascending or descending order: " << endl ;  
    // use for loop to iterate values  
    for ( i = 0 ; i < num ; i++ )  
    {  
        cout << " arr [ " << i << " ] = " ;  
        cin >> arr [ i ] ;   
    }  
    // initialize the starting and ending variable's values  
    st = 0 ;  
    end = num - 1 ; // size of array ( num ) - 1  
    // define the item or value to be search  
    cout << " Define a value to be searched from sorted array: " << endl ;  
    cin >> tgt ;  
    // use while loop to check 'st', should be less than equal to 'end'.  
    while ( st < = end )  
    {  
        // get middle value by splitting into half  
        mid = ( st + end ) / 2 ;  
        /* if we get the target value at mid index, print the position and exit from the program. */  
        if ( arr [ mid ] == tgt )  
        {  
            cout << " element is found at index " << ( mid + 1 ) ;  
            exit ( 0 ) ;  // use for exit program the program  
        }  
        // check the value of target element is greater than the mid element' value  
        else if ( tgt > arr [ mid ] )  
        {  
            st = mid + 1 ; // set the new value for st variable  
        }  
        // check the value of target element is less than the mid element' value  
        else if ( tgt < arr [ mid ] )  
        {  
            end = mid - 1 ; // set the new value for end variable  
        }  
    }  
    cout << " Number is not found. " << endl ;  
    return 0 ;  
}   

OUTPUT:

Define the size of the array: 
10
enter the values in sorted array either ascending or descending order:
Arr [ 0 ]  = 12
Arr [ 1 ]  = 24
Arr [ 2 ]  = 36
Arr [ 3 ]  = 48
Arr [ 4 ]  = 50
Arr [ 5 ]  = 54
Arr [ 6 ]  = 58
Arr [ 7 ]  = 60
Arr [ 8 ]  = 72
Arr [ 9 ]  = 84
Define a value to be searched from sorted array:
50
element is found at index 5
……………………………………………………………………..
Process executed in 2.22 seconds
Press any key to continue.

Explanation:

In the above example of a program in C++, search for a element in a sorted array. First we find the middle element and then comparing our element or key with the middle element if the key is les then middle element then we bring the end pointer from last element to mid+1 and performing the procedure again till we find the element or the key.

Example 4: Another type of iterative function program for binary search in C++:

#include < bits/stdc++.h >
#include < stdio >
#include < stdlib >
#include < vector >
#include < iostream >
using namespace std ; 
int binarySearch ( vector < int > v , int To_Find )
{
	int lo = 0 , hi = v.size ( ) - 1 ;
	int mid ;
	// This below check covers all cases , so need to check
	// for mid = lo - ( hi - lo ) / 2
	while ( hi - lo > 1 ) {
		int mid = ( hi + lo ) / 2 ;
		if ( v [ mid ] < To_Find ) {
			lo = mid + 1 ;
		}
		else {
			hi = mid ;
		}
	}
	if ( v [ lo ] == To_Find ) {
		cout << "Found"
			<< " At Index " << lo << endl ;
	}
	else if ( v [ hi ] == To_Find ) {
		cout << "Found"
			<< " At Index " << hi << endl ;
	}
	else {
		cout << "Not Found" << endl ;
	}
}
int main ( )
{
	vector < int > v = { 1 , 3 , 4 , 5 , 6 } ;
	int To_Find = 1 ;
	binarySearch ( v , To_Find ) ;
	To_Find = 6 ;
	binarySearch ( v , To_Find ) ;
	To_Find = 10 ;
	binarySearch ( v , To_Find ) ;
	return 0 ;
}

OUTPUT:

Found At Index 0
Found At Index 4
Not Found
……………………….
Process executed in 2.22 seconds
Press any key to continue. 

Explanation

In the above example of a program in C++, we have used vector instead of array and using to_find function but using while loop and using mid pointer as we have discussed which is created by initializing lo pointer at index 0 and hi at index n-1, where n is the length of the vector. If the element which we want to find is the element which is present at the middle element, then middle element is our element or the key.

Example 3: A program that uses a user-defined function to execute a binary search.

/* program to find the specified element from the sorted array using the binary search in C++. */  
#include < iostream >  
using namespace std ;  
/* create user-defined function and pass different parameters: 
arr [ ] - it represents the sorted array; 
num variable represents the size of an array; 
tgt variable represents the target or specified variable to be searched in the sorted array. */  
int bin_search ( int arr [ ] , int num , int tgt )  
{  
    int beg = 0 , end = num – 1 ;   
    // use loop to check all sorted elements  
    while ( beg < = end )  
    {  
        /* get the mid value of sorted array and then compares with target element. */  
        int mid = ( beg + end ) / 2 ;         
        if ( tgt = = arr [ mid ] )  
        {  
            return mid ; // when mid is equal to tgt value  
        }         
        // check tgt is less than mid value, discard left element  
        else if ( tgt < arr [ mid ] )  
        {  
            end = mid – 1 ;  
        }         
        // if the target is greater than the mid value, discard all elements  
        else {  
            beg = mid + 1 ;  
        }  
    }  
    // return -1 when target is not exists in the array  
    return -1 ;  
}  
int main ( )  
{  
    // declaration of the arrays  
    int arr [ ] = { 5 , 10 , 15 , 20 , 25 , 30 , 37 , 40 } ;  
    int tgt = 25 ; // specified the target element     
    int num = sizeof ( arr ) / sizeof ( arr [ 0 ] ) ;  
    // declare pos variable to get the position of the specified element  
    int pos = bin_search ( arr , num , tgt ) ;     
    if ( pos ! = 1 )  
    {  
        cout << " element is found at position " << ( pos + 1 ) << endl;  
    }  
    else  
    {  
        cout << " element is not found in the array" << endl ;  
    }  
    return 0 ;  
}  

OUTPUT:

element is found at position 5
……………………………………………
Process executed in 2.22 seconds
Press any key to conitinue.

Explanation

We defined an array arr [ ] = { 5 , 10 , 15 , 20 , 25 , 30 , 35 , 40 } in the preceding program, and then we supplied number '25' as the number to seek from the sorted array using the binary search method. As a result, we write the bin search ( ) user-defined function, which searches the supplied integer and returns the message "Element is located at position 5". The bin search ( ) method returns "Element not found in the array" if the number is not specified in the array.

Example 4: Using the recursion function, discover the requested element:

Let's look at an example of utilizing the binary search within the recursion function to see if the provided element is found in the sorted array.

/* find the specified number using the binary search technique inside the recursion method. */  
#include < iostream > 
#include < bits/stdc++.h >
#include < stdlib >
#include < stdio > 
using namespace std;  
// define a function  
int binary_search ( int [ ] , int , int , int ) ;  
int main ( )  
{  
    // declaration of the variables  
    int i , arr [ 100 ] , tgt , num , ind , st , end ;  
    cout << " Define the size of an array: " ;  
    cin >> num ;     
    cout << " enter " << num << " elements in ascending order: " << endl ;  
    // use for loop to ieterate the number  
    for ( i = 0 ; i < num ; i++ )  
    {  
        cout << " arr [ " << i << " ] = " ;  
        cin >> arr [ i ] ;  
    }  
    // define the element to be search  
    cout << " \n enter an element to be searched in ascending array: " ;  
    cin >> tgt ;     
    // ind define the index number  
    ind = binary_search ( arr , 0 , num - 1 , tgt) ;   
    // check for existemce of the specified element  
    if ( ind = = 0 )  
        cout << tgt << " is not available in the array-list" ;     
    else  
        cout << tgt << " is available at position " << ind << endl ;  
    return 0 ;  
}  
// function defnition  
int binary_search ( int arr [ ] , int st , int end , int tgt )  
{  
    int mid ;  
    // check st is greater than end  
    if ( st > end )  
    {  
        return 0 ;  
    }  
    mid = ( st + end ) / 2 ; // get middle value of the sorted array  
      
    // check middle value is equal to target number  
    if (arr [ mid ] == tgt )  
    {  
        return ( mid + 1 ) ;  
    }  
    // check mid is greater than target number  
    else if ( arr [ mid ] > tgt )  
    {  
        binary_search ( arr , st , mid - 1 , tgt ) ;  
    }  
    // check mid is less than target number  
    else if ( arr [ mid ] < tgt )  
    {  
        binary_search ( arr , mid + 1 , end , tgt ) ;   
    }  
}

OUTPUT:

Define the size of an array: 10
Arr [ 0 ] = 2
Arr [ 1 ] = 4
Arr [ 2 ] = 5
Arr [ 3 ] = 8
Arr [ 4 ] = 12
Arr [ 5 ] = 13
Arr [ 6 ] = 27
Arr [ 7 ] = 36
Arr [ 8 ] = 49
Arr [ 9 ] = 51
enter an element to be searched in ascending array: 12
12 is available at position 6.
…………………………………………………………………………………
Process executed in 2.22 seconds
Press any key to continue.

Explanation

We input all items of an array in ascending order in the aforementioned software, and then define a number as the target element, which is '12,' which is found from a sorted array using the binary search method. As a result, we develop the binary search () user-defined function, which searches an array for the given element's location and returns the specific element accessible at that point. It also returns 0 if the element isn't found in the sorted array.



ADVERTISEMENT
ADVERTISEMENT