0
What else can I help you with?
Call by reference using pointer in c plus plus?
Example: void foo( MyClass& object ){} // function with call by reference signature MyClass* p = new MyClass(); // instantiate a pointer to MyClass foo( *p ); // call by reference using the pointer
When does this pointer get created?
When we call non static method with respect to class object then this pointer is created which keep the reference of that object.
When would you use a pointer and a reference variable?
pointer: to access data by address reference: there is no reference in C language
How can you change values in call by reference?
We don't call by reference, we call functions. The arguments passed to the function are passed (not called) either by value or by reference, depending upon the function signature (the prototype). When you pass by reference you are passing the actual variable, not a copy of the variable, thus the function can modify that variable's value directly. The only exception is when the parameter is declared a constant reference. Passing a pointer is essentially the same as passing by reference, however the pointer itself is passed by value. To pass a pointer by reference you must pass a pointer-to-pointer instead. Passing by value always copies the value, whether it is declared constant or not. But if it is declared constant, the function might as well accept a constant reference. Passing objects (instances of a class) by constant value will incur a performance penalty in making an unnecessary copy. If it is constant, there is little point in copying the object.
Should you explicitly call a destructor in C programming?
Not to be pedantic, but you cannot call a destructor explicitly. Destructors are implicitly called when an object falls from scope or when you delete a pointer to an object. Any object created dynamically (with the new keyword) must be deleted as soon as you are finished with it, and before the pointer falls from scope. In this sense, you are explicitly calling the object's destructor, however it's really being called implicitly by you deleting the pointer. It's also good practice to explicitly NULL your pointer immediately after deleting the object it pointed to. An object reference is destroyed automatically when the reference falls from scope. If you have a pointer to that reference, do not delete the pointer, but do assign it to NULL as soon as possible to prevent any access to the deleted object. If you do delete a pointer to a reference that's still in scope, you will render the reference NULL and a NULL reference will render your program invalid.
Why you pass something by reference and then make it const while call by reference mean you want to change it?
Call by reference does not necessarily mean you want to change something. It simply means that you are passing a pointer to the object rather than the object itself. This can be cost effective if the object is large, in comparison to a pointer. Making the call by reference const is an effective tool for doing this when you do not intend to modify the object, and you want to make sure you don't accidentally do so.
What is a reference variable in c plus plus?
A reference variable in C++ is a formal parameter of a function call that automatically dereferences itself, as if it were a pointer, into a reference to the original value in the calling routine. You declare the reference type in the function declaration and prototype, but the compiler automatically adds the reference (&) operator on call, and the dereference (*) operator on use.
What happens if we use an integer pointer as a member of structure instead of structure pointer?
By declaring an integer pointer you are declaring that any non-zero reference stored in the pointer is guaranteed to be an integer reference. In order to guarantee the reference is actually a structure, the pointer must be declared as such, because casting an integer to a structure can never be regarded as being type-safe.
Explain reference variable and how it is different from pointer variable?
In JAVA, all variables are reference variables, and there are no pointer variables. Even though the platform may implement them as pointers, they are not available as such. In C, no variables are reference variables. They are a C++ enhancement. In C++ a reference variable is syntactically the same as a pointer variable, except that the use of the indirection operator (*) is implicit. You do declare reference variables slightly differently than pointer variables but, once you do so, they can be treated as non-pointer variables. Reference variables also cannot be redefined once they have been initialized to point to some object. They are const. Structurally, there is no difference between a pointer variable and a reference variable. They are both still pointers. The compiler just makes it easier to treat reference variables and non-pointer variables the same way.
Do functions get called by reference only?
No. Function parameters are passed by value. Always. Even the so called "call by reference" is a value - the value of the pointer or the address of the object - but what is placed in the parameter list is a value.
What is dangling pointer reference in c plus plus?
A dangling pointer (we also use the terms stray pointer and wild pointer) is created whenever we call delete on a pointer and then try to use the pointer without reassigning it.We can also create dangling pointers inadvertently by calling a rogue function that returns a pointer to an object that is local to the function we are calling. The object will fall from scope when the function returns so the pointer is left dangling.Note that there is no such thing as a dangling pointer reference. Pointers and references are not the same. A reference is merely an alias to an object -- it consumes no memory beyond the object it refers to. Whereas a pointer is a variable that may contain the address of an object, but it requires additional memory to do so (4 bytes on 32-bit architecture). Pointers may be NULL, references can never be NULL. Pointers to valid objects require indirection, references do not. References are the preferred method of accessing an object's members, not least because they are easier to work with.
WHAT IS POINTER TO POINTER IN C POINTER?
Pointer in C is Memory Reference. It stores memory address of any variable, constant, function or something you later use in your programming. Pointer basically used to ease the referencing of variables and others or in polymorphism and inheritance.
