Newbie "new" nuisance

[Sharke]

I'm currently going through a C++ primer and one of the exercises was to create storage of various types using "new," to print the addresses and then delete them. Here is my code:

#include <iostream>
using namespace std;

int main()
{
	int* i = new int;
	long* l = new long;
	char* c = new char;
	float* f = new float[100];

	cout << "Address of i: " << i << endl;
	cout << "Address of l: " << l << endl;
	cout << "Address of c: " << c << endl;
	cout << "Address of f: " << f << endl;

	delete i;
	delete l;
	delete c;
	delete f;

	getchar();
	return 0;
}

It prints the address fine except for the pointer to char. This is what I get:

Address of i: 007D4B50
Address of l: 007D4B90
Address of c: ═²²²²½½½½½½½½■ε■
Address of f: 007D4C10

How come the char* is printing as garbage?

[hk_mp5kpdw]

When printing a char pointer, cout tries to print a string (null terminated array of characters starting at the address given). This is different behavior than in the other cases. Try this:

cout << "Address of c: " <<  reinterpret_cast<void*>(c) << endl;

float* f = new float[100];

...

delete f;

That last bit needs to be delete [] f since you've allocated an array of elements and not just a single one.

[Sharke]

Aha! That all makes sense and thanks for reminding me about the delete []f.

However - do I have to use a "reinterpret_cast"? It works OK with a simple (void*) cast too.

[laserlight]

However - do I have to use a "reinterpret_cast"? It works OK with a simple (void*) cast too.

You should use reinterpret_cast as it is easier to spot, more ugly, and the C++ style casts document your intentions better.