equation3-2-2.cpp

This is solution code c++ in class lesson.

#include<iostream>
using namespace std;
int main()
{   
    string input;
    cout << "Enter a number (-128 to 127): ";
    cin >> input;
    string tmp;
    int value = 0;
    int sign = 1;
    if (input.at(0) == '-')
    {
        tmp = input.substr(1,3);
        sign = -1;
    }
    else
    {
        tmp = input;
        sign = 1;
    }
    int len = tmp.length();
    if (len == 3)
       value = (int)(tmp.at(0) - '0') * 100 +
               (int)(tmp.at(1) - '0') * 10 +
               (int)(tmp.at(2) - '0');
    else if(len == 2)
        value = (int)(tmp.at(0) - '0') * 10 +
                (int)(tmp.at(1) - '0');
    else if(len == 1)
        value = (int)(tmp.at(0) - '0');
    else{
         cout << "Wrong format number" << endl;
         system("pause");
         return 0;
    }
    int num = 0;
    if (sign == -1)
       num = 128 - value;
    else
       num = value;
    int bit1=0,bit2=0,bit3=0,bit4=0,bit5=0,bit6=0,bit7=0;
    
    bit7 = num % 2;
    num = num / 2;
    bit6 = num % 2;
    num = num / 2;
    bit5 = num % 2;
    num = num / 2;
    bit4 = num % 2;
    num = num / 2;
    bit3 = num % 2;
    num = num / 2;
    bit2 = num % 2;
    num = num / 2;
    bit1 = num % 2;
    num = num / 2;
    if (sign == -1)
       cout << "1" << bit1 << bit2 << bit3 << bit4 << bit5 << bit6 << bit7;
    else
       cout << "0" << bit1 << bit2 << bit3 << bit4 << bit5 << bit6 << bit7;
    cout << endl;
    system("pause");
    return 0;
}