debug error heap corruption c++ pointers - c++

Question

so i have this assignment that tells the user to input two numbers and lets him choose some basic operations(like a calculator) from a menu.
The goal of this exercise is to help us get more familiar with pointers/pointers to functions/dynamic allocation...The professor prefers that we use the "malloc" and "calloc" commands.
There is a part I'm stuck on, the part of displaying the history. It works for the first execution, but gives a debugging error as the code proceeds. Is there anyone who can help me solve the issue?
c++ code:
#include <iostream>
using namespace std;
//structure for the history array
struct Operation{
float result;
int choice;
};
float add(float, float);
float sub(float, float);
float mult(float, float);
float divi(float, float);
int main(){
//size1=for 1st history array, size2=for 2nd history array, t=to check if an operation was done at least once
int choice,size1=0,t=0,i,size2=0;
//pointer to func
int(*operation)(int, int);
float a, b,result;
//pointers set to NULL
Operation *history1 = NULL, *history1i = NULL, *history2 = NULL, *history2i = NULL;
cout << "Enter 2 numbers a & b: ";
cin >> a >> b;
cout << "What would you like to do?" << endl << "1=Addition" << endl << "2=Subtraction" << endl << "3=Division" << endl;
cout << "4=Multiplication" << endl << "5=Display History" << endl << "6=Exit" << endl;
do{
cin >> choice;
//initialize the size of 1st array if a choice is valid
if (choice < 5 && choice >0)
size1++;
//initialize 1st array
history1 = (Operation*)calloc(size1, sizeof(Operation));
if (history1 == NULL){
cout << "History allocation failed."<<endl;
exit(0);
}
//menu
switch (choice){
case 1: result = (add)(a, b);
cout << endl << "The addition of " << a << " & " << b << " gives: " << result << endl;
break;
case 2:result = (sub)(a, b);
cout << endl << "The subtraction of " << a << " & " << b << " gives: " << result << endl;
break;
case 3:if (b != 0){
result = (divi)(a, b);
cout << endl << "The division of " << a << " & " << b << " gives: " << result << endl;
}
else
cout << "Can't perform the divison.";
break;
case 4:result = (mult)(a, b);
cout << endl << "The multiplication of " << a << " & " << b << " gives: " << result << endl;
break;
//display history
case 5:if (t == 1){
cout << endl << "Your history is: " << endl;
for (history2i = history2,i=1; (history2i - history2) < size2; history2i++,i++){
cout << "\t"<<i<<"- " << a;
if (history2i->choice == 1)
cout << " + ";
else if (history2i->choice == 2)
cout << " - ";
else if (history2i->choice == 3)
cout << " / ";
else
cout << " * ";
cout << b << " = " << history2i->result<<endl;
}
}
else
cout <<endl<< "You haven't done any calcualtions yet."<<endl;
break;
case 6:break;
default:cout << endl << "The option you entered is not valid." << endl;
break;
}
//if choice is valid
if (choice < 5 && choice >0){
//if at least one opertion executed copy the elements of history2 in history1
if (t == 1){
for (history1i = history1, history2i = history2; (history1i - history1) < size2; history1i++, history2i++){
history1i->result = history2i->result;
history1i->choice = history2i->choice;
}
history1i++;//in order to enter the new operation
}
//if no operation done
else{
history1i = history1;
}
history1i->result = result;
history1i->choice = choice;
}
//if at least one operation done=>history exists and not NULL
if (t == 1){
free(history2);//in order to create a new array with the new elements
history2 = NULL;
}
//if not operations done before increment t
if (choice < 5 && choice >0 && t == 0){
t++;
}
//if valid choice create history 2
if (choice < 5 && choice >0){
size2 = size1;
history2 = (Operation*)calloc(size2, sizeof(Operation));
if (history2 == NULL){
cout << "History allocation failed." << endl;
exit(0);
}
//store all the previous history including the new one
for (history2i = history2, history1i = history1; (history2i - history2) < size2; history2i++, history1i++){
history2i->result = history1i->result;
history2i->choice = history1i->choice;
}
}
free(history1);
history1 = NULL;
if (choice != 6)
cout << endl << "Choose another option: ";
} while (choice != 6);
return 0;
}
float add(float a, float b){
return a + b;
}
float sub(float a, float b){
return a - b;
}
float mult(float a, float b){
return a*b;
}
float divi(float a, float b){
return a / b;
}