Многократно определенный символ

class Substance{
    friend Substance operator + (Substance& x, Substance& y);
private:
    char* matter;
    char* type;
    double ftemp;
    double stemp;
public:
    Substance(char* = 0, char* = 0, double = 0, double = 0);    
    Substance(const Substance&);
    int operator == (const Substance&);
    Substance& operator = (const Substance&);
    char* GetM();
    char* GetT();
    double GetF() { return ftemp; }
    double GetS() { return stemp; }
    void Set(char*,char* ,double ,double);
    void Show();
    ~Substance();
};

#include "Substance.h"
#include "stdio.h"
#include <cstring>
 
Substance::Substance(char* str, char* let, double x, double y) {
    if (str) {
        matter = new char[strlen(str) + 1];
        strcpy(matter, str);
    }
    else
        matter = 0;
    if (let) {
        type = new char[strlen(let) + 1];
        strcpy(type, let);
    }
    else
        type = 0;
    ftemp = x;
    stemp = y;
    printf("The default constructor have worked\n");
}
Substance::Substance(const Substance& newbie) {
    if (!newbie.matter || !newbie.type)
        printf("Error class determination doesn`t finished\n");
    else {
        delete[] matter;
        matter = new char[strlen(newbie.matter) + 1];
        strcpy(matter, newbie.matter);
        delete[] type;
        type = new char[strlen(newbie.type) + 1];
        strcpy(type, newbie.type);
        ftemp = newbie.ftemp;
        stemp = newbie.stemp;
        //return newbie;
        printf("The copy constructor have worked\n");
    }
}
char * Substance::GetM()
{
    char* s = new char[strlen(matter) + 1];
    strcpy(s, matter);
    return s;
}
char * Substance::GetT()
{
    char* v = new char[strlen(type) + 1];
    strcpy(v, matter);
    return v;
}
Substance::~Substance() {
    if (matter) delete[] matter;
    if (type) delete[] type;
}
void Substance::Set(char* str, char* let, double x, double y) {
    if (matter != 0) delete[] matter;
    if (str) {
        matter = new char[strlen(str) + 1];
        strcpy(matter, str);
    }
    else
        matter = 0;
    if (type != 0) delete[] type;
    if (let) {
        type = new char[strlen(let) + 1];
        strcpy(type, let);
    }
    else
        type = 0;
    if (x <= y && x >= -273.0) {
        ftemp = x;
        stemp = y;
    }
    else
        y = x;
}
void Substance::Show() {
    printf("%s %s %f - %f\n", matter, type, ftemp, stemp);
}
 
Substance& Substance::operator= (const Substance& nw) {
        if (&nw == this) return *this;
            if (nw.matter || nw.type) {
                delete[] matter;
                matter = new char[strlen(nw.matter) + 1];
                strcpy(matter, nw.matter);
                delete[] type;
                type = new char[strlen(nw.type) + 1];
                strcpy(type, nw.type);
                ftemp = nw.ftemp;
                stemp = nw.stemp;
            }
        else
            {
                printf("Error 2nd class isn`t created\n");
            }
        return *this;
}
 
int Substance::operator==(const Substance& y) {
    if (strcmp(matter, y.matter) == 1 && strcmp(type, y.type) == 1 && ftemp == y.ftemp && stemp == y.stemp) return 0;
    else return 1;
}

#include "Substance.cpp"
#include <iostream>
#include "conio.h"
 
Substance operator+ (Substance& x, Substance& y) {
    Substance buf;
    buf.ftemp = x.ftemp + y.ftemp;
    buf.stemp = x.stemp + y.stemp;
    buf.matter = new char[strlen(x.matter) + strlen(y.matter) + 1];
    strcpy(buf.matter, x.matter);
    strcat(buf.matter, y.matter);
    buf.type= new char[strlen(x.type) + strlen(y.type) + 1];
    strcpy(buf.type, x.type);
    strcat(buf.type, y.type);
    return Substance();
}
int main()
{
    Substance A;
    char ce[20];
    printf("Enter the name of chemical element\n");
    scanf("%s",&ce);
    char tce[2];
    do {
        printf("Enter the type of the chemical element\nM-Metal A-Alloy C-Compoud\n");
        scanf("%s", &tce);
    } while (tce=="M" || tce == "A" || tce == "C");
    double x,y;
    printf("Enter the lower limit of the transition of the substance to the superconducting state\n");
    scanf("%f", &x);
    printf("Enter the upper limit of the transition of the substance to the superconducting state\n");
    scanf("%f", &y);
    A.Set(ce,tce,x,y);
    A.Show();
    char* string= 0;
    double num = 0;
    string = A.GetM();
    printf("Name of chemical element: %s\n", string);
    string = A.GetT();
    printf("Type of the chemical element: %s\n", string);
    num = A.GetF();
    printf("Lower temperature: %f\n", num);
    num = A.GetS();
    printf("Higher temperature: %f\n", num);
    printf("Try to copy from A to B with '='\n");
    Substance B;
    B = A;
    printf("A:");
    A.Show();
    printf("B:");
    B.Show();
    printf("Lets compare this objects with '=='\n");
    int rez = 0;
    rez = A == B;
    if (rez == 0)printf("Theyre equal\n");
    else printf("Theyre not equal\n");
    printf("Finally, let's put them together\n");
    Substance C;
    C = A + B;
    C.Show();
    _getch();
    return 0;
}

#include "Substance.h"

    scanf("%lf", &x);
    scanf("%lf", &y);