2019. A. calc, base number systems

// C program to convert a number from any base
// to decimal
#include <iostream>
#include <stdio.h>
#include <string>
#include <string.h>
#include <cstdlib>
#include <cstring>
#include <sstream>      // std::stringstream
#include <vector>
#include <algorithm>
using namespace std;

int state = 0;
int signPosition =0;
int equalSignPosition = 1;

#define ADDITION 1
#define MULTIPLICATION 2

vector <int> outputV; // Vector for the output
long sstoi(const char *s) // custom stoi function
{
    long i;
    i = 0;
    while(*s >= '0' && *s <= '9')
    {
        i = i * 10 + (*s - '0');
        s++;
    }
    return i;
}


int getFirstNumber(string input, int signPos)
{
    string newString = input.substr(0,signPos);
    int firstNum = sstoi(newString.c_str());
    return firstNum;
   // cout << "Return first num: " << firstNum << endl;
}

int getSecondNumber(string input, int signPos)
{
    string newString = input.substr(signPos+1, equalSignPosition-signPosition-1);
    int secondNum = sstoi(newString.c_str());
    return secondNum;
}

int getThirdNumber(string input, int equalSignPos)
{
    string newString = input.substr(equalSignPos+1);
    int thirdNumber = sstoi(newString.c_str());
    return thirdNumber;
}

int val(char c)
{
    if (c >= '0' && c <= '9')
        return (int)c - '0';
    else
        return (int)c - 'A' + 10;
}

// Function to convert a number from given base 'b'
// to decimal
int toDeci(char *str, int base)
{
    int len = strlen(str);
    int power = 1; // Initialize power of base
    int num = 0; // Initialize result
    int i;

    // Decimal equivalent is str[len-1]*1 +
    // str[len-1]*base + str[len-1]*(base^2) + ...
    for (i = len - 1; i >= 0; i--)
    {
        // A digit in input number must be
        // less than number's base
        if (val(str[i]) >= base)
        {
        //printf("Invalid Number");
        return -1;
        }

        num += val(str[i]) * power;
        power = power * base;
    }

    return num;
}

// Driver code
int main()
{

    /*
    char str[] = "21";
    int base = 3;
    printf("Decimal equivalent of %s in base %d is "
        " %d\n", str, base, toDeci(str, base));
    return 0;
    */
    int broiTestove = 0;
    cin >> broiTestove;
    cin.ignore();
    string input;
    while(getline(cin, input)){
   // cin.ignore();
    if(input.empty())
        break;

    equalSignPosition = input.find('=');
    if(input.find('+')!=-1)
    {
       state = ADDITION;
        signPosition = input.find('+');
    }

    if(input.find('*')!=-1)
    {
        state = MULTIPLICATION;
        signPosition = input.find('*');
     //   cout << "sign * " << endl;
    }


    int firstNum = getFirstNumber(input, signPosition);
    int secondNum = getSecondNumber(input,++signPosition);
    int thirdNum = getThirdNumber(input,++equalSignPosition);

   // cout << "First number: " << firstNum << " second number: " << secondNum << " third number " << thirdNum << endl;

    //Converting the numbers above from int type to char arrays, bcs toDeci() works with char arrays
    string firstNumString;
    string secondNumString;
    string thirdNumString;
    firstNumString = to_string(firstNum);
    secondNumString =  to_string(secondNum);
    thirdNumString =  to_string(thirdNum);
    char inputCharArrayFirstNumber[firstNumString.size() + 1];
    strcpy(inputCharArrayFirstNumber, firstNumString.c_str());  // or pass &s[0]
    char inputCharArraySecondNumber[secondNumString.size() + 1];
    strcpy(inputCharArraySecondNumber, secondNumString.c_str());    // or pass &s[0]
    char inputCharArrayThirdNumber[thirdNumString.size() + 1];
    strcpy(inputCharArrayThirdNumber, thirdNumString.c_str());  // or pass &s[0]

    //cout << "predi fora" << endl;

    for(int i =2; i<=10; i++)
    {
       // cout << endl;
        //cout << " for index: " << i << " ";
        int firstConvertedNumber = toDeci(inputCharArrayFirstNumber, i);
       // cout << "first converted number " << firstConvertedNumber << " ";
        int secondConvertedNumber = toDeci(inputCharArraySecondNumber, i);
       // cout << "second converted number " << secondConvertedNumber << " ";
        int thirdConvertedNumber = toDeci(inputCharArrayThirdNumber, i);
       // cout << "third converted number " << thirdConvertedNumber;

        if((firstConvertedNumber!=-1) && (secondConvertedNumber!=-1)&& (thirdConvertedNumber!=-1))
            //toDeci() returns -1 if the current digit in it's cycle is greater than the base
            // for example the max digit in number system with base 3 is 2. For base 2 - 1 and etc.

        {
            if(state == ADDITION)
            {
                if((firstConvertedNumber + secondConvertedNumber) == thirdConvertedNumber)
                {
                    outputV.push_back(i);
                }
            }

            if(state == MULTIPLICATION)
            {
                if((firstConvertedNumber * secondConvertedNumber) == thirdConvertedNumber)
                {
                    outputV.push_back(i);
                }
            }
        } // end if-a -1

    }
    sort(outputV.begin(), outputV.end());
  //  cout << endl << "Otpechatvame: " << endl;
    for(int i =0; i<outputV.size();i++)
    {
        cout << outputV[i] << " ";
    }
    outputV.clear();
    cout << endl;
    }// end while



}