﻿ C++ Exercises: Find two's complement of a binary number - w3resource

# C++ Exercises: Find two's complement of a binary number

## C++ For Loop: Exercise-65 with Solution

Write a program in C++ to find the two's complement of a binary number.

Sample Solution:-

C++ Code :

``````#include <iostream> // Including the input/output stream library
#define SZ 8 // Defining a constant named SZ with a value of 8

using namespace std; // Using the standard namespace

int main() // Main function where the execution of the program starts
{
// Declare variables and character arrays to store binary values and their complements
char bn[SZ + 1], onComp[SZ + 1], twComp[SZ + 1];
int i, carr = 1; // Declare variables for iteration and carry initialization
int er = 0; // Initialize an error flag

// Display messages asking for input
cout << "\n\n Find two's complement of a binary value:\n";
cout << "----------------------------------------------\n";
cout << " Input a " << SZ << " bit binary value: ";
cin >> bn; // Read a binary value from the user

// Loop to find the one's complement of the entered binary value
for (i = 0; i < SZ; i++)
{
// Check each bit of the input binary number and create its one's complement
if (bn[i] == '1')
{
onComp[i] = '0';
}
else if (bn[i] == '0')
{
onComp[i] = '1';
}
else
{
cout << "Invalid Input. Input the value of assign bits." << endl; // Display an error message
er = 1; // Set error flag to 1
break; // Exit the loop
}
}
onComp[SZ] = '\0'; // Assign null terminator at the end of the one's complement array

// Loop to find the two's complement of the one's complement
for (i = SZ - 1; i >= 0; i--)
{
// Check each bit of the one's complement to calculate the two's complement
if (onComp[i] == '1' && carr == 1)
{
twComp[i] = '0';
}
else if (onComp[i] == '0' && carr == 1)
{
twComp[i] = '1';
carr = 0;
}
else
{
twComp[i] = onComp[i];
}
}
twComp[SZ] = '\0'; // Assign null terminator at the end of the two's complement array

// If no error occurred during input processing, display the original binary value, one's complement, and two's complement
if (er == 0)
{
cout << " The original binary = " << bn << endl;
cout << " After ones complement the value = " << onComp << endl;
cout << " After twos complement the value = " << twComp << endl;
}
}
``````

Sample Output:

``` Find two's complement of a binary value:
----------------------------------------------
Input a 8 bit binary value: 01101110
The original binary = 01101110
After ones complement the value = 10010001
After twos complement the value = 10010010
```

Flowchart:

C++ Code Editor: