Bai 7.12 C++

#include<stdio.h>
#include<conio.h>
#include<math.h>
#include<process.h>
#include<iostream.h>


typedef struct diem
{
double x,y;
};

double DD(diem a,diem b)
{
double d;
d = sqrt(((a.x - b.x)*(a.x - b.x)) + ((a.y - b.y)*(a.y - b.y)));
return d;
}

class tamgiac
{
private:
diem a,b,c;
public:
tamgiac(){}
void nhap();
void kiemtra();
void chuvi();
void dientich();
~tamgiac(){}
};
void tamgiac::nhap()
{
cout<<"\nNhap toa do diem A: "; cin>>a.x>>a.y;
cout<<"\nNhap toa do diem B: "; cin>>b.x>>b.y;
cout<<"\nNhap toa do diem C: "; cin>>c.x>>c.y;
}

void tamgiac::kiemtra()
{
double x,y,z;

x=DD(a,b);y=DD(a,c);z=DD(b,c);
if(x>0 && y>0 && z>0)
{
if((x+y<z) || (x+z<y) || (y+z<x))
{
cout<<"\nKhong phai la tam giac"; getch(); exit(0);
}
}
else
{
cout<<"\nKhong phai la tam giac"; getch(); exit(0);
}
}

void tamgiac::chuvi()
{
double cv;
cv= DD(a,b)+DD(a,c)+DD(b,c);
cout<<"\nChu Vi: "<<cv;
}

void tamgiac::dientich()
{
double dt;
dt=(DD(a,b)+DD(a,c)+DD(b,c))/2;
dt = sqrt(dt*(dt-DD(a,b))*(dt-DD(b,c))*(dt-DD(a,c)));
cout<<"\nDien Tich: "<<dt;
}



void main()
{
tamgiac tg;
clrscr();
tg.nhap();
tg.kiemtra();
tg.chuvi();
tg.dientich();
getch();
}

Theo mình nên sửa như này thì hay hơn:
#include
#include
#include
#include
#include


typedef struct diem
{
double x,y;
};

double DD(diem a,diem b)
{
double d;
d = sqrt(((a.x - b.x)*(a.x - b.x)) + ((a.y - b.y)*(a.y - b.y)));
return d;
}

class tamgiac
{
private:
diem a,b,c;
public:
tamgiac(){}
void nhap();
void kiemtra();
void chuvi();
void dientich();
~tamgiac(){}
};
void tamgiac::nhap()
{
cout<<"\nNhap toa do diem A: "; cin>>a.x>>a.y;
cout<<"\nNhap toa do diem B: "; cin>>b.x>>b.y;
cout<<"\nNhap toa do diem C: "; cin>>c.x>>c.y;
}

void tamgiac::kiemtra()
{
double x,y,z;

x=DD(a,b);y=DD(a,c);z=DD(b,c);
if(x>0 && y>0 && z>0)
{
if((x+y{
cout<<"\nKhong phai la tam giac"; getch(); exit(0);
}
}
else
{
cout<<"\nKhong phai la tam giac"; getch(); exit(0);
}
}

void tamgiac::chuvi()
{
double cv;
cv= DD(a,b)+DD(a,c)+DD(b,c);
cout<<"\nChu Vi: "<}

void tamgiac::dientich()
{
double dt;
dt=(DD(a,b)+DD(a,c)+DD(b,c))/2;
dt = sqrt(dt*(dt-DD(a,b))*(dt-DD(b,c))*(dt-DD(a,c)));
cout<<"\nDien Tich: "<}



void main()
{
tamgiac tg;
char ck;
do
{
clrscr();
tg.nhap();
tg.kiemtra();
tg.chuvi();
tg.dientich();
cout<<"\nBan co muon tiep tuc ko (C/K)?";
cin>>ck;
}while (ck=='c'||ck=='C');
}