question3-2-3.cpp

This is solution code c++ in class lesson.

#include<iostream>
using namespace std;
int getDecValue(char ch);
string getBinValue(char ch);
int main()
{ 
    string input;
    cout << "Enter a number (in Hexadecimal): ";
    cin >> input;
    int decValue = 0;
    decValue = getDecValue(input.at(0)) * 4096 + 
               getDecValue(input.at(1)) * 256 +
               getDecValue(input.at(2)) * 16 +
               getDecValue(input.at(3));
    cout << "The decimal number of " << input << " is " 
         << decValue << endl;
    cout << "The binary number of " << input << " is "
         << getBinValue(input.at(0)) << getBinValue(input.at(1))
         << getBinValue(input.at(2)) << getBinValue(input.at(3))<< endl;
    
    system("pause");
    return 0;
}
int getDecValue(char ch)
{
    switch(ch){
    case 'F': return 15;
    case 'E': return 14;
    case 'D': return 13;
    case 'C': return 12;
    case 'B': return 11;
    case 'A': return 10;
    case '9': return 9;
    case '8': return 8;    
    case '7': return 7;
    case '6': return 6;
    case '5': return 5;
    case '4': return 4;
    case '3': return 3;
    case '2': return 2;
    case '1': return 1;
    case '0': return 0;
    }
    return -1;
} 
string getBinValue(char ch)
{
    switch(ch){
    case 'F': return "1111";
    case 'E': return "1110";
    case 'D': return "1101";
    case 'C': return "1100";
    case 'B': return "1011";
    case 'A': return "1010";
    case '9': return "1001";
    case '8': return "1000";    
    case '7': return "0111";
    case '6': return "0110";
    case '5': return "0101";
    case '4': return "0100";
    case '3': return "0011";
    case '2': return "0010";
    case '1': return "0001";
    case '0': return "0000";
    }
    return "0000";
}