Quintessention

#include "stdafx.h"
#include <iostream>
#include <cstring>
#include <cctype>
using namespace std;

class str_type {
    char string[80];
public:
    str_type(char *str = "") { strcpy(string, str); }
    str_type operator+(str_type op_r);
    str_type operator+(char *str);
    str_type operator=(str_type op_r);
    str_type operator=(char *str);
    str_type operator-(str_type op_r);
    void show() { cout << string; }
    friend str_type operator+(char *str, str_type obj);
};

str_type str_type::operator+(str_type op_r)
{
    str_type temp;
    strcpy(temp.string, string);
    strcat(temp.string, op_r.string);
    return temp;
}

str_type str_type::operator+(char *str)
{
    str_type temp;
    strcpy(temp.string, string);
    strcat(temp.string, str);
    return temp;
}

str_type str_type::operator=(str_type op_r)
{
    strcpy(string, op_r.string);
    return *this;
}

str_type str_type::operator=(char *str)
{
    strcpy(string, str);
    return *this;
}

str_type str_type::operator-(str_type op_r)
{
    str_type temp;
    char *s_ptr = string;
    char BUF[80];
    int buf_i = 0;

    while (*s_ptr != '\0') // It runs until the end of LEFT OBJECT string
    {
        while (isalpha(*s_ptr)) // Scaning one word
        {
            BUF[buf_i] = *s_ptr;
            buf_i++;
            s_ptr++;
        }
        if (buf_i > 0) // If word
            BUF[buf_i] = '\0';
        else {        // If symbol
            BUF[buf_i] = *s_ptr;
            BUF[buf_i + 1] = '\0';
        }
        if (strcmp(op_r.string, BUF)) // Compare word with RIGHT OBJECT string
            strcat(temp.string, BUF);

        if (buf_i == 0) s_ptr++; // Next pointer position if current position is symbol
        buf_i = 0; // Reset buffer for writing
    }

    return temp;
}

str_type operator+(char *str, str_type obj)
{
    str_type temp;
    strcat(temp.string, str);
    strcat(temp.string, obj.string);

    return temp;
}

int main()
{
    str_type ob1("It is very-very hard test"), ob2("very"), ob_res;

    ob_res = ob1 - ob2;

    cout << "Source: "; ob1.show();
    cout << "\nDelete from source: "; ob2.show();
    cout << "\nResult: "; ob_res.show();

    cout << "\n\n";
    str_type newob("Added: ");
    newob = newob + "First";
    newob.show();

    cout << "\n\n";
    newob = "Also " + newob;
    newob.show();

    cout << "\n";
    system("pause");
    return 0;
}