Page 252 - DCAP404 _Object Oriented Programming

Unit 11: Pointers and Dynamic Memory Management

for (n=0; n<i; n++) Notes
{
cout << “Enter number: “;
cin >> p[n];
}
cout << “You have entered: “;
for (n=0; n<i; n++)
cout << p[n] << “, “;
delete[] p;
}
return 0;
} How many numbers would you like to type? 5
Enter number : 75
Enter number : 436

Enter number : 1067
Enter number : 8
Enter number : 32
You have entered: 75, 436, 1067, 8, 32,
Notice how the value within brackets in the new statement is a variable value entered by the
user (i), not a constant value:
p= new (nothrow) int[i];
But the user could have entered a value for i so big that our system could not handle it. For
example, when I tried to give a value of 1 billion to the “How many numbers” question, my
system could not allocate that much memory for the program and I got the text message we
prepared for this case (Error: memory could not be allocated).

Notes Remember that in the case that we tried to allocate the memory without specifying
the nothrow parameter in the new expression, an exception would be thrown, which if it’s
not handled terminates the program.
It is a good practice to always check if a dynamic memory block was successfully allocated.
Therefore, if you use the nothrow method, you should always check the value of the pointer
returned. Otherwise, use the exception method, even if you do not handle the exception. This
way, the program will terminate at that point without causing the unexpected results of continuing
executing a code that assumes a block of memory to have been allocated when in fact it has not.

11.5.2 The this Pointer

C++ uses a unique keyword called “this” to represent an object that invokes a member function.
‘this’ is a pointer that points to the object on which this function was called. The pointer ‘this’
acts as an implicit argument to all the member function apart from the explicit arguments
passed to it.

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