Can we subtract two pointer variables?

The subtraction of two pointers is possible only when they have the same data type. The result is generated by calculating the difference between the addresses of the two pointers and calculating how many bits of data it is according to the pointer data type.

What happens when you subtract two pointers?

When two pointers are subtracted, both shall point to elements of the same array object, or one past the last element of the array object; the result is the difference of the subscripts of the two array elements. Note that when allowed, the result is the subscripts difference.

Why is the addition of two pointers impossible?

Because pointers represent locations in the memory. Each pointer is the address of a block in the memory. Subtracting two pointers will give you the size of memory between them. Addition or any other mathematical operation on values of pointers has no meaning.

Can you add and subtract pointers in C?

We can perform arithmetic operations on the pointers like addition, subtraction, etc. However, as we know that pointer contains the address, the result of an arithmetic operation performed on the pointer will also be a pointer if the other operand is of type integer.

What is invalid about pointer?

An invalid pointer reference occurs when a pointer’s value is referenced even though the pointer doesn’t point to a valid block. One way to create this error is to say p=q;, when q is uninitialized. The pointer p will then become uninitialized as well, and any reference to *p is an invalid pointer reference.

IS null always defined as 0 zero )?

The null pointer constant is always 0. The NULL macro may be defined by the implementation as a naked 0 , or a cast expression like (void *) 0 , or some other zero-valued integer expression (hence the “implementation defined” language in the standard). The null pointer value may be something other than 0.

Can we multiply two pointers?

yes it is allowed, *x is not a pointer but a value pointed by x . and hence *x+*y; is addition of two values pointed by x and y . It multiplies or divides the pointed at values, and the pointed at values are not pointers, so multiplication and division is fine.

Can two pointer variables be added?

It is not legal to add two pointers…

Can you add pointers together why would you?

No, you can t add pointers together. If you try to perform this type of calculation with pointers in a C program, your compiler will complain. The only time the addition of pointers might come up is if you try to add a pointer and the difference of two pointers.

Which of the following operations is are invalid on pointer variable?

Pointer arithmetic is not valid one. Pointer addition, multiplication and division are not allowed as these are not making any sense in pointer arithmetic.

How do you check if a pointer is valid or not?

if you cannot guarantee a pointer is valid, check that it is non-0 before indirecting it. when deleting objects, set the pointer to 0 after deletion. be careful of object ownership issues when passing pointers to other functions.

What is NullPointerException in Java?

NullPointerException is a runtime exception in Java that occurs when a variable is accessed which is not pointing to any object and refers to nothing or null. Since the NullPointerException is a runtime exception, it doesn’t need to be caught and handled explicitly in application code.