Bad Access Error on XCode C++ - c++

Question

I am trying to implement a Polynomial structure using a linked list of Terms (the linked list is implemented separately).
When I run my main program, I get a (Thread 1: EXC_BAD_ACCESS code=2) error on the line
coeff = x; in the definition my setCoeff function.
I tried commenting out that specific function call, but it gives me the same error for the setX() and setY() functions.
I think I have my files and functions set up properly, I cannot figure out why it is not letting me use these functions.
Please help !
In order, I have included: Polynomial.h, Polynomial.cpp, and main.cpp.
#ifndef __Polynomial__Polynomial__
#define __Polynomial__Polynomial__
#include <stdio.h>
class Term {
private:
int coeff;
int deg_x;
int deg_y;
public:
Term();
int getCoeff();
int getX();
int getY();
void setX(int);
void setY(int);
void setCoeff(int);
};
#endif /* defined(__Polynomial__Polynomial__) */
___________________________
#include "Polynomial.h"
Term::Term() {
coeff = NULL;
deg_x = NULL;
deg_y = NULL;
}
int Term::getCoeff(){
return coeff;
}
int Term::getX() {
return deg_x;
}
int Term::getY() {
return deg_y;
}
void Term::setX(int x){
deg_x = x;
}
void Term::setY(int x){
deg_y = x;
}
void Term::setCoeff(int x){
coeff = x;
}
__________________________
#include <iostream>
#include <fstream>
#include "Polynomial.h"
int main() {
Term* t1;
t1->setCoeff(4);
t1->setX(3);
t1->setY(6);
}

Answer 1

You never create an object. You have Term* t1, which is an uninitialized pointer to random memory, then you try to use it with t1->setCoeff(4) which is trying to use an object that was never created. That's definitely gonna go wrong.
Do this instead..
auto t1 = std::make_unique<Term>();
Or if you don't need it to be a pointer, you can create a simple stack variable and access it with '.' operator like this ...
Term t1;
t1.setCoeff(4);
t1.setX(3);
t1.setY(6);