# 13505 - String Calculator(class) 2
>author: Utin
###### tags: `class`
---

## Brief
See the code below

## Solution 0

#include <iostream>
#include "function.h"

std::string arr = "0123456789abcdefghijklmnopqrstuvwxyz";

String_Calculator::String_Calculator(const std::string str) : s(str) {}

String_Calculator& String_Calculator::Add(const string add) {
    this->s += add;
    return *this;
}

String_Calculator& String_Calculator::Subtract(const string sub) {
    size_t pos = this->s.find(sub, 0);
    if (pos == string::npos) this->s = "error";
    else this->s.erase(pos, sub.size());
    return *this;
}

String_Calculator& String_Calculator::Shift(const string shift) {
    for (int i = 0; i < shift.size(); i++) {
        if (!isdigit(shift[i])) {
            this->s = "error";
            return *this;
        }
    }
    int shift_bits = stoi(shift);
    shift_bits %= arr.size();
    for (int i = 0; i < this->s.size(); i++) {
        for (int j = 0; j < arr.size(); j++) {
            if (this->s[i] == arr[j]) {
                int idx = j + shift_bits;
                if (idx >= arr.size()) idx -= arr.size();
                this->s[i] = arr[idx];
                break;
            }
        }
    }
    return *this;
}

void String_Calculator::output() const {
    cout << s << '\n';
}

// Utin

## Reference