alreadyDefined&wrongInputInfLoop

#include <iostream>
#include <string>
//1: Here is Mainirk.cpp

#include <windows.h>
#include "include/irrKlang.h"
#include <conio.h>
#include "stats.h"

#pragma comment(lib, "irrKlang.lib")
using namespace std;
using namespace irrklang;


int choose();
void charmander1();
void bulbasaur1();
void squirtle1();
void yourpokemon();
void enemypokemon();
void battle();
void bchoice();
void aichoice();

void attack();
void defend();
double y;
double z;


double m;
double n;

int achoice;


pokemon charmander (25,3);
pokemon bulbasaur (20,4);
pokemon squirtle (30,2);



int main()
{
choose();
yourpokemon();
cout<<"\nPress any key to continue.";
_getch();
system("cls");
cout<<"Your rival Chuy walks in and challenges you to a battle\n\n";
_getch();

do
{
battle();
aichoice();
_getch();
}
while (y>0 && m>0);

return 0;
}




int choose()
{

cout<<"Choose your pokemon!!!\n\n";
cout<<"********************************\n\n";
cout<<" Charmander has "<<charmander.hp()<<" hp and "<<charmander.dmg()<<" damage.\n\n";

cout<<" Bulbasaur has "<<bulbasaur.hp()<<" hp and "<<bulbasaur.dmg()<<" damage.\n\n";

cout<<" Squirtle has "<<squirtle.hp()<<" hp and "<<squirtle.dmg()<<" damage.\n\n";
cout<<"--------------------------------\n\n";

cout<<"Type [a] to choose Charmander\n\n";

cout<<"Type [b] to choose Bulbasaur\n\n";

cout<<"Type [c] to choose Squirtle\n\n";
char answer;
cin>>answer;


 if (answer == 'a'||answer == 'A')
 {
 answer = 'a';
 }

 if (answer == 'b'||answer == 'B')
 {
 answer = 'b';
 }

 if (answer == 'c'||answer == 'C')
 {
 answer = 'c';
 }



 switch (answer)
 {
 if (answer =='a')
 {
 case 'a': charmander1();
  y= charmander.hp();
  z= charmander.dmg();
  m= squirtle.hp();
  n= squirtle.dmg();
 }
 if (answer == 'b')
 {
 case 'b': bulbasaur1();
 y = bulbasaur.hp();
 z = bulbasaur.dmg();
 m = charmander.hp();
 n = charmander.dmg();
 }
 if (answer == 'c')
 {
 case 'c': squirtle1();
 y = squirtle.hp();
 z = squirtle.dmg();
 m = bulbasaur.hp();
 n = bulbasaur.dmg();
 }
 }return 0;
 }

  void charmander1()
 {
 cout<<"You have chosen the Pokemon Charmander!!!\n";
 cout<<"Charmander is a fire type!\n";
 }

 void bulbasaur1()
 {
 cout<<"You have chosen the Pokemon Bulbasaur!!!\n";
 cout<<"Bulbasaur is a grass type!\n";
 }

 void squirtle1()
 {
 cout<<"You have chosen the Pokemon Squirtle!!!\n";
 cout<<"Squirtle is a water type!\n";
 }

 void yourpokemon()
 {

 cout<<"HP is "<<y<<" and damage is "<<z;
 }



 void battle()
 {
 cout<<"\n\t\tStatus\t\t";
 cout<<"\n-----------------------\n";
 cout<<"Your Pokemon\t\tEnemy Pokemon\n";
 cout<<"HP: "<<y<<"\t\tHP: "<<m<<"\n";
 ISoundEngine* se = createIrrKlangDevice();
	se->play2D("Kalimba.mp3");


 bchoice();
 }

 void bchoice()
 {
 cout<<"\n\nType 1 to attack or 2 to defend\n";

 cin>>achoice;

 if (achoice ==1)
 {
 attack();
 }
 else if (achoice ==2)
 {
 defend();
 }
 else
 {
 cout<<"Retype your choice"<<endl;

 }
 }

 void attack()
 {
 m = m-z;
 cout<<"\nYour Pokemon attacks!";
 }

 void defend()
 {
 cout<<"\nYour pokemon defends!";
 }



 void aichoice()
 {
 if (achoice ==1)
 {
 cout<<"\nThe enemy pokemon attacks!";
 y = (y-n);
 }


 else if (achoice ==2)
 {
 cout<<"\nThe enemy pokemon defends!";
 }
 }



// 2. Here is stats.h

#include <iostream>
using namespace std;

class pokemon
{
int health, damage;

public:

pokemon (int,int);
int hp()
{
return (health);
}

int dmg()
{
return (damage);
}

};

pokemon::pokemon (int hp, int dmg)
{
health = hp;
damage = dmg;
}