Problem Statement
When a user enters a number, display the number in all the number system formats from binary, octal, decimal, and hexadecimal.
Concepts and Explanation
The program converts a number from one base (binary, octal, decimal, or hexadecimal) to other bases. It uses two functions, convert_to_decimal and convert_to_base_x, to perform the conversions. It also takes user input for the initial base and the number.
Header file
#include : The iostream header file is included to use the standard input and output library functions, such as cin and cout for taking input and displaying output.
Using namespace std
using namespace std;: This line allows the program to use the standard C++ library's namespace, which includes common functions and classes like cin, cout, and string without explicitly prefixing them with std::.
convert_to_decimal function
The convert_to_decimal function takes an integer number and its base as arguments and converts it to its decimal equivalent. It initializes a variable result to store the decimal value and a variable i as a multiplier. It then iterates using a while loop until the input number becomes zero. In each iteration, it calculates the remainder c and updates the number and multiplier i. The remainder is multiplied by the multiplier, and the result is added to the result.
convert_to_base_x function
The convert_to_base_x function takes a decimal integer number and the target base as arguments and converts the decimal number to the given base. It initializes a string result to store the result and an array hex_digits to map the hexadecimal digits. The function iterates using a while loop until the input number becomes zero. In each iteration, it calculates the remainder c and updates the number. The remainder is then used as an index to get the corresponding character from hex_digits, and the character is added to the result string.
main function
The main function is the entry point of the program. It begins by declaring two integer variables, input_base and input_number. The program then prompts the user to enter the base of the number (2 for binary, 8 for octal, 10 for decimal, or 16 for hexadecimal) and the number itself. These values are stored in input_base and input_number, respectively.
Next, the program calculates the decimal equivalent of the input number. If the input base is not 10 (i.e., not decimal), it calls the convert_to_decimal function with the input number and base as arguments to convert it to decimal. If the input base is already decimal, it directly assigns the input number to decimal_number.
The program then converts and displays the decimal number in binary, octal, and hexadecimal representations using the convert_to_base_x function. The function is called with decimal_number and the target base (2 for binary, 8 for octal, and 16 for hexadecimal) as arguments. The results are displayed using cout.
Finally, the main function returns 0, indicating that the program has executed successfully.
Ending the Program
Once the loop has finished iterating through all the digits, the program prints a success message and returns 0, indicating that the program has executed successfully.
Method 1
Code
/*
* -----------------------------------------------------------
* OOPS using C++ Language (CSU1287P)
* Instructor: Dr. Pankaj Vaidya | Author: Divya Mohan
*
* This code is a part of the educational initiative by dmj.one
* with aim of empowering and inspiring learners in the field of
* Computer Science and Engineering through the respective courses.
*
* (c) 2022, Divya Mohan for dmj.one. All rights reserved.
* -----------------------------------------------------------
*/
#include <iostream>
using namespace std;
int convert_to_decimal(int number, int base)
{
int result = 0, i = 1;
while (number != 0)
{
int c = number % 10;
result += c * i;
number /= 10;
i *= base;
}
return result;
}
string convert_to_base_x(int number, int base)
{
string result = "";
char hex_digits[] = "0123456789ABCDEF";
while (number != 0)
{
int c = number % base;
result = hex_digits[c] + result;
number /= base;
}
return result;
}
int main()
{
cout << "This program converts a number between different bases (binary, octal, decimal, and hexadecimal).";
int input_base, input_number;
cout << "Enter the base (2, 8, 10, 16) and the number you want to convert - (Example: 2 1101) - and press Enter: ";
cin >> input_base >> input_number;
int decimal_number = (input_base != 10) ? convert_to_decimal(input_number, input_base) : input_number;
cout << "Decimal: " << decimal_number << endl;
cout << "Binary: " << convert_to_base_x(decimal_number, 2) << endl;
cout << "Octal: " << convert_to_base_x(decimal_number, 8) << endl;
cout << "Hexadecimal: " << convert_to_base_x(decimal_number, 16) << endl;
return 0;
}
Method 2: Using While Loop
#include <iostream>
#include <string>
using namespace std;
int binaryToDecimal(const string &binary) {
int decimal = 0;
for (char digit : binary) {
decimal = decimal * 2 + (digit - '0');
}
return decimal;
}
string decimalToBinary(int decimal) {
string binary;
while (decimal > 0) {
binary = to_string(decimal % 2) + binary;
decimal /= 2;
}
return binary;
}
string decimalToOctal(int decimal) {
string octal;
while (decimal > 0) {
octal = to_string(decimal % 8) + octal;
decimal /= 8;
}
return octal;
}
string decimalToHexadecimal(int decimal) {
string hex;
const char *hex_digits = "0123456789ABCDEF";
while (decimal > 0) {
hex = hex_digits[decimal % 16] + hex;
decimal /= 16;
}
return hex;
}
int main() {
string input, format;
cout << "Enter a number: ";
cin >> input;
cout << "Enter the number format (decimal, binary, octal, hexadecimal): ";
cin >> format;
int decimal = 0;
if (format == "hexadecimal" || format == "Hexadecimal" || input.find("0x") == 0 || input.find("0X") == 0) {
for (size_t i = input.find_first_not_of("0x0X"), len = input.length(); i < len; ++i) {
char c = input[i];
decimal = decimal * 16 + (c >= '0' && c <= '9' ? c - '0' : c >= 'A' && c <= 'F' ? c - 'A' + 10 : c - 'a' + 10);
}
} else if (format == "octal" || format == "Octal" || input[0] == '0') {
for (size_t i = input.find_first_not_of('0'), len = input.length(); i < len; ++i) {
decimal = decimal * 8 + (input[i] - '0');
}
} else if (format == "binary" || format == "Binary") {
decimal = binaryToDecimal(input);
} else if (format == "decimal" || format == "Decimal") {
for (char c : input) {
decimal = decimal * 10 + (c - '0');
}
} else {
cerr << "Invalid format. Please enter a valid format (decimal, binary, octal, hexadecimal)." << endl;
return 1;
}
cout << "Decimal: " << decimal << endl;
cout << "Binary: " << decimalToBinary(decimal) << endl;
cout << "Octal: " << decimalToOctal(decimal) << endl;
cout << "Hexadecimal: " << decimalToHexadecimal(decimal) << endl;
return 0;
}
Method 3: Using menu list.
#include
using namespace std;
string decimal_to_base_x(int n, int x)
{
string result = "";
char hex_digits[] = "0123456789ABCDEF";
while (n != 0)
{
int c = n % x;
result = hex_digits[c] + result;
n /= x;
}
return result;
}
int binary_to_decimal(int n)
{
int result = 0, i = 1;
while (n != 0)
{
int c = n % 10;
result += c * i;
n /= 10;
i *= 2;
}
return result;
}
void dectoall()
{
int decimal_number;
cout << "Enter a decimal number: ";
cin >> decimal_number;
cout << "Binary: " << decimal_to_base_x(decimal_number, 2) << endl;
cout << "Octal: " << decimal_to_base_x(decimal_number, 8) << endl;
cout << "Hexadecimal: " << decimal_to_base_x(decimal_number, 16) << endl;
}
void bintoall()
{
int binary_number;
cout << "Enter a binary number: ";
cin >> binary_number;
int decimal_from_binary = binary_to_decimal(binary_number);
cout << "Decimal: " << decimal_from_binary << endl;
cout << "Octal: " << decimal_to_base_x(decimal_from_binary, 8) << endl;
cout << "Hexadecimal: " << decimal_to_base_x(decimal_from_binary, 16) << endl;
}
int main()
{
int n;
cout << "Menu:\n 1. Binary to decimal, octal, hexadecimal.\n 2. Decimal to Binary, Octal, hexadecimal\n.Enter a valid operation:";
cin >> n;
switch (n)
{
case 1:
bintoall();
break;
case 2:
dectoall();
break;
default:
cout << "Enter a valid number";
break;
}
return 0;
}
Method 4: Using constructors
#include <iostream>
using namespace std;
class NumberConverter
{
private:
int input_base;
int input_number;
int binary_to_decimal(int n)
{
int result = 0, i = 1;
while (n != 0)
{
int c = n % 10;
result += c * i;
n /= 10;
i *= 2;
}
return result;
}
string decimal_to_base_x(int n, int x)
{
string result = "";
char hex_digits[] = "0123456789ABCDEF";
while (n != 0)
{
int c = n % x;
result = hex_digits[c] + result;
n /= x;
}
return result;
}
public:
NumberConverter(int base, int number) : input_base(base), input_number(number)
{
}
void convert_and_display()
{
int decimal_number;
if (input_base == 2)
{
decimal_number = binary_to_decimal(input_number);
}
else
{
decimal_number = input_number;
}
cout << "Decimal: " << decimal_number << endl;
cout << "Binary: " << decimal_to_base_x(decimal_number, 2) << endl;
cout << "Octal: " << decimal_to_base_x(decimal_number, 8) << endl;
cout << "Hexadecimal: " << decimal_to_base_x(decimal_number, 16) << endl;
}
};
int main()
{
int input_base, input_number;
cout << "Enter the base of the number you are entering (2, 8, 10, 16): ";
cin >> input_base;
cout << "Enter the number: ";
cin >> input_number;
NumberConverter converter(input_base, input_number);
converter.convert_and_display();
return 0;
}Method 5: Autodetect inputted number and output converted number
Does not work for decimal number 10, 100 and any other varients which uses only 1 and 0
#include <iostream>
#include <string>
#include <bitset>
#include <sstream>
#include <iomanip>
using namespace std;
int main()
{
string input;
cout << "Enter a number: ";
cin >> input;
stringstream ss;
ss << input;
int decimal = 0;
bool is_hex = false, is_octal = false, is_binary = false;
if (input.find("0x") == 0 || input.find("0X") == 0)
{
is_hex = true;
ss >> hex >> decimal;
}
else if (input[0] == '0')
{
is_octal = true;
ss >> oct >> decimal;
}
else
{
for (char c : input)
{
if (c != '0' && c != '1')
{
is_binary = false;
break;
}
is_binary = true;
}
if (is_binary)
{
bitset<32> binary(input);
decimal = binary.to_ulong();
}
else
{
ss >> decimal;
}
}
cout << "Decimal: " << decimal << endl;
cout << "Binary: " << bitset<32>(decimal) << endl;
cout << "Octal: " << oct << decimal << endl;
cout << "Hexadecimal: " << hex << uppercase << decimal << endl;
return 0;
}Method 6: Manual input of number type with sstream usage
#include <iostream>
#include <string>
#include <bitset>
#include <sstream>
#include <iomanip>
using namespace std;
int main()
{
string input, format;
cout << "Enter a number: ";
cin >> input;
cout << "Enter the number format (decimal, binary, octal, hexadecimal): ";
cin >> format;
stringstream ss;
ss << input;
int decimal = 0;
if (format == "hexadecimal" || format == "Hexadecimal" || input.find("0x") == 0 || input.find("0X") == 0)
{
ss >> hex >> decimal;
}
else if (format == "octal" || format == "Octal" || input[0] == '0')
{
ss >> oct >> decimal;
}
else if (format == "binary" || format == "Binary")
{
bitset<32> binary(input);
decimal = binary.to_ulong();
}
else if (format == "decimal" || format == "Decimal")
{
ss >> decimal;
}
else
{
cerr << "Invalid format. Please enter a valid format (decimal, binary, octal, hexadecimal)." << endl;
return 1;
}
cout << "Decimal: " << decimal << endl;
cout << "Binary: " << bitset<32>(decimal) << endl;
cout << "Octal: " << oct << decimal << endl;
cout << "Hexadecimal: " << hex << uppercase << decimal << endl;
return 0;
}Method 7: Using string and sstream headers
#include <iostream>
#include <sstream>
#include <string>
using namespace std;
int binaryToDecimal(const string &binary)
{
int decimal = 0;
for (char digit : binary)
{
decimal = decimal * 2 + (digit - '0');
}
return decimal;
}
string decimalToBinary(int decimal)
{
string binary;
while (decimal > 0)
{
binary = to_string(decimal % 2) + binary;
decimal /= 2;
}
return binary;
}
string decimalToOctal(int decimal)
{
string octal;
while (decimal > 0)
{
octal = to_string(decimal % 8) + octal;
decimal /= 8;
}
return octal;
}
string decimalToHexadecimal(int decimal)
{
string hex;
const char *hex_digits = "0123456789ABCDEF";
while (decimal > 0)
{
hex = hex_digits[decimal % 16] + hex;
decimal /= 16;
}
return hex;
}
int main()
{
string input, format;
cout << "Enter a number: ";
cin >> input;
cout << "Enter the number format (decimal, binary, octal, hexadecimal): ";
cin >> format;
int decimal = 0;
if (format == "hexadecimal" || format == "Hexadecimal" || input.find("0x") == 0 || input.find("0X") == 0)
{
stringstream ss(input);
ss >> hex >> decimal;
}
else if (format == "octal" || format == "Octal" || input[0] == '0')
{
stringstream ss(input);
ss >> oct >> decimal;
}
else if (format == "binary" || format == "Binary")
{
decimal = binaryToDecimal(input);
}
else if (format == "decimal" || format == "Decimal")
{
stringstream ss(input);
ss >> decimal;
}
else
{
cerr << "Invalid format. Please enter a valid format (decimal, binary, octal, hexadecimal)." << endl;
return 1;
}
cout << "Decimal: " << decimal << endl;
cout << "Binary: " << decimalToBinary(decimal) << endl;
cout << "Octal: " << decimalToOctal(decimal) << endl;
cout << "Hexadecimal: " << decimalToHexadecimal(decimal) << endl;
return 0;
}Method 8: Using Only the main function
#include <iostream>
using namespace std;
int main()
{
int input_base, input_number;
cout << "Enter the base of the number (2, 8, 10, 16): ";
cin >> input_base;
cout << "Enter the number: ";
cin >> input_number;
int decimal_number = 0, multiplier = 1;
for (int n = input_number; n != 0; n /= 10)
{
int c = n % 10;
decimal_number += c * multiplier;
multiplier *= input_base;
}
string bases[] = {"Binary", "Octal", "Decimal", "Hexadecimal"};
int base_values[] = {2, 8, 10, 16};
for (int i = 0; i < 4; i++)
{
int base = base_values[i];
string result = "";
char hex_digits[] = "0123456789ABCDEF";
for (int n = decimal_number; n != 0; n /= base)
{
int c = n % base;
result = hex_digits[c] + result;
}
cout << bases[i] << ": " << result << endl;
}
return 0;
}Output for Method 1:
This program converts a number between different bases (binary, octal, decimal, and hexadecimal).
Enter the base (2, 8, 10, 16) and the number you want to convert - (Example: 2 1101) - : 10 15
Decimal: 15
Binary: 1111
Octal: 17
Hexadecimal: F