I need help editing a code for c++

[I need to get the following message When (ABC) is lower than base 13] plus i want to see if it can work with decimals as well.

here is the code

#include #include #include #include  using namespace std; /* This Class represents the Number in a Number System and also provides the facility to convert the Number system associated with that Number i.e. conversion from any Base to any other base like, octal to hexa or hexa to decimal etc. */ struct Number { // Contains the number as string std::string m_data; // Contains the internal base int m_base; // Calculates the power of given number int powerOf(int val, int power) { if (power == 0) return 1; int result = val; for (int i = 1; i < power; i++) { result = result*val; } return result; } public: Number(std::string num, int base = 10) : m_base(base), m_data(num) {} int getBase() const { return m_base; } const std::string& getData() const { return m_data; } // Convert the internal number to decimal base and returns the number // according to decimal number system. int getDecimalValue() { int decValue = 0; for (int i = m_data.size() - 1; i >= 0; i--) { if (m_data[i] >= 'A' && m_data[i] < 'Z') decValue = decValue + (m_data[i] - 'A' + 10)*powerOf(m_base, (m_data.size() - 1 - i)); else decValue = decValue + (m_data[i] - '0')*powerOf(m_base, (m_data.size() - 1 - i)); } return decValue; } // This API will convert the existing base in Number system to any other base bool convertBase(int newBase) { if (newBase > (10 + 'Z' - 'A')) { std::cout << "Conversion Not Possible for Base Greater Than " << (10 + 'Z' - 'A') << std::endl; return false; } int decValue = getDecimalValue(); std::string newValue = ""; while (decValue > 0) { int rem = decValue % newBase; decValue = decValue / newBase; char newChar = '0' + rem; if (newChar > '9') { newChar = 'A' + (newChar - '9') - 1; } newValue += newChar; } std::reverse(newValue.begin(), newValue.end()); m_data = newValue; m_base = newBase; return true; } }; int main() { bool flag = true; string input; cout << "This is a program to read and write integer numbers in different bases." << endl << endl; while (flag) { string original = ""; char yn; int target_base = 0; string x = ""; string arr[2]; int base = 0; int i = 0; cout << "Type in an integer number in the format(n)b "; cin >> input; original = input; cout << "What is the target base? "; cin >> target_base; input = input.substr(1); std::istringstream ins(input); std::string out; i = out.length(); i = 2; while (ins.good() && i!=0) { getline(ins, out, ')'); if (!out.empty()) { i = i - 1; arr[i] = out; } } stringstream geek(arr[0]); geek >> base; Number numObj(arr[1], base); numObj.convertBase(target_base); cout << original << " = (" << numObj.getData() << ")" << numObj.getBase()<> yn; if (yn == 'n' || yn == 'N') { flag = false; } cout << endl< 
Example output:
 
Type in an integer number in the format (n)b:
 
(ABC)5
 
!!! Invalid number.... the digits are out of range. !