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Answered 2010-01-05 02:06:49

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.

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A reference variable is a variable that refers to another variable. int x = 7; int &r = x; r would be a reference to x. If you change the value of x the value of r will change and the other way around. A reference will always be the same as the variable it refers to.

Declare the type (int, char, double, etc) followed by the name of the variable. The variable name is a reference to the memory allocated to the type being declared. If the variable is a pointer to the type, precede the name with *. In C++, you may also initialise variables in the declaration.

An alias is a reference, an alternate name for a variable or constant. You can assign the address of any variable or constant to a reference of the same type. A reference is a bit like a constant pointer to the type but, unlike a pointer, a reference has no address of its own thus you cannot store references. More importantly, references can never be NULL. They are simply an alternative name by which you can refer to an existing variable or constant. When you assign a value to an existing reference to a variable, you are assigning the value to the variable itself. When you pass a reference to a function, you are passing the address of the value being referred to, and that address is assigned to the function's reference argument and is local to the function. This is not unlike passing a pointer, but pointers may be NULL, references are guaranteed to be non-NULL (a NULL reference invalidates your program). Note that C++ references are not the same as C reference variables or constants. In C, a reference variable is simply a non-const pointer, while a reference constant is a constant pointer. Hence pointers can be dereferenced (both in C and C++). But in C++, a reference is neither a variable nor a pointer, but is constant (it always refers to the same object and cannot be reassigned once assigned).

A reference is an alias for a variable. Unlike a pointer variable, which must occupy memory in order to store the memory address of the object it points to, a reference consumes no memory other than that used by the object it references. An array name is a typical example of a reference. It is an alias to the memory allocated to the array.

Call by reference means calling a function using a reference to a variable or a pointer. You call a function by passing refrences to a variable. For eg: void x(int &a) { a=2; } void main() { int s=3; x(s); } OR void a(int &c) { c=5;}void main(){ int *p; *p=2a(*p);}

Reference VariableIt does not have separate memory other than variableIt is just an alias created to existing variableIt is not present C languagePointer VariableIt has separate memory other than variableIt actually stores address of the variableIt is present in C as well as C++.

There are 5 type of variables in C++....

A variable is a named memory location for which the contents are volatile. The antonym of variable is constant.

A constant is a variable that does not change. The correct term is constant variable.

pointer: to access data by address reference: there is no reference in C language

type variable {[optional array size]} {= optional initializer};

I can tell you that it is not an illegal variable name in C. I do not currently have a C++ compiler installed, but I would assume that it would also be valid in C++.

A variable is a place to store a value that may change while the a program runs.

Not initialized variable: int myInt; Initialized variable: int myInt = 10;

same the types used in C. that is int...char...float...

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.

A static member variable is local to the class rather than to an object of the class.

Pass by value, constant value, reference and constant reference. Pass by value is the default in C++ (pass by reference is the default in Java).

The reference variable controls an object. Without the reference variable, you would have no way of accessing the object.

Strictly speaking, a reference is not a variable of any kind, thus there is no such thing as a "reference variable". A variable is a memory address in which we can store a single value whereas a reference is simply an alternate name for an existing variable.

Its type, its value and its memory address.

It is impossible to give any decimal/numeric value if we are not given the values of at least one variable, so the answer is B + B + B + C + C + C.

There is no such thing as a constant variable. A value is either constant or it is variable, it cannot be both. To answer the question, a constant value cannot be changed anywhere in a C++ program. Only variable values can be changed.

The scope of a variable is the range, or area, in which a variable exists. // this c is global and can be referenced from anywhere int c = 1; void foo() { // this c is local to function foo and can't be referenced from the outside int c = 2; } void bar() { // if we try to reference c here, we get the value 1 from the global variable }

There is no difference, other than that declarations in C++ can also initialise the variable in a single instruction. C example: int x; // declaration x=5; // initialisation C++ example: int y=5; // declaration and initialisation combined.

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