precondition and post condition check

[George2]

Hello everyone,


I am looking for a good sample about how to implement C++ pre-condition and post condition check, but can not find a good sample code. Do you have any referred ones?

Since I can not find, I wrote the patterns in two ways, I am not sure which is correct and if both are not correct, how to implement this pattern?

Sample code 1,

#define MAX 1024

class Base
{
public:
	void foo(int i)
	{
	if (i > MAX)
	{
		// error handling
	}
	else
	{
		do_foo(i);
	}
}

private:
	virtual void do_foo(int i) = 0;
};

class Derived : public Base
{
private:
	virtual void do_foo(int i)
	{
	// i is never > MAX here
	}
};

int main()
{
	Derived d;
	d.foo (1000);

	return 0;
}

Sample 2,

#define MAX 1024

class Base
{
public:
	void foo(int i)
	{
	if (i > MAX)
	{
		// error handling
	}
	else
	{
		do_foo(i);
	}
}

private:
	virtual void do_foo(int i) = 0;
};

class Derived : public Base
{
public:
	virtual void do_foo(int i)
	{
		foo (i);
		// i is never > MAX here
	}
};

int main()
{
	Derived d;
	d.do_foo (1000);

	return 0;
}

thanks in advance,
George