What is register variable in c language?

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Register variables are a special case of automatic variables. Automatic variables are allocated storage in the memory of the computer; however, for most computers, accessing data in memory is considerably slower than processing in the CPU. These computers often have small amounts of storage within the CPU itself where data can be stored and accessed quickly. These storage cells are called registers. Normally, the compiler determines what data is to be stored in the registers of the CPU at what times. However, the C language provides the storage class register so that the programmer can ``suggest'' to the compiler that particular automatic variables should be allocated to CPU registers, if possible. Thus, register variables provide a certain control over efficiency of program execution. Variables which are used repeatedly or whose access times are critical, may be declared to be of storage class register. Also these register variables are used in huge projects the tiny program developers are not interested to include these register variables, because the tiny programs never requires more time complete its job. These register variables may be used to store constant values so as to make use of it anywhere in the programs. main{ register float a=0;}
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In C Language if you write int a; a10; then which is Declaration and which is Definition of variable a?

the declaration is int a - you are declaring a variable type integer. Definition is when you define a variable or give it a value, so a = 10 would be a definition Answer i have an doubt.. i have read somewhere that whenever memory allocation takes place , it is called definition. and declaration (MORE)

What is register variable?

Answer . register - Asks the compiler to devote a processor register to this variable in order to speed the program's execution. The compiler may not comply and the variable looses it contents and identity when the function it which it is defined terminates.. - niv

What are register variables?

A register variables is that which got space in CPU internal register sets this requst can be granted or rejected by CPU ,by register veriable the processing speed become much faster for that variable.

How you can interchange two integer values using swap variable in c language?

Answer . t = a; a = b; b = t; // t is a third integer variable (swap variable) But here's a way without a swap variable, given as as a macro in C: #define SWAP(a,b) { if (a!=b) { a^=b; b^=a; a^=b; }} // Swap macro by XOR Once you define it, you can say swap(x,y) to swap x and y. The num (MORE)

What is the difference between local and global variable of C language?

4m Sai.. Gloabal Variable is variable which is declared before main ().. int a=10;. main(). {. }. here a is a global variable. where ever u r using this variable ... we'll get the value as 10.. Local Variable is a variable which is declared inside the main().. int a=10;. main(). {. int a= (MORE)

What does static variable mean in c language?

there are 3 main uses for the static.. 1. If you declare within a function:. It retains the value between function calls. 2.If it is declared for a function name:. By default function is extern..so it will be visible from other files if the. function declaration is as static..it is invisible fo (MORE)

How do you identify the register variables?

Registry variables can be identified with registry allocation. Theprogrammer will decide on the variables that need to be assigned tothe registry, and variables not assigned to the registry will beheld in RAM.

Difference between register variable and automatic variables?

Register variables are stored in register of microprocessor/micro-controller. The read/write access to register variable is the fastest because CPU never need any memory BUS operation to access these variable. Auto variable are stored in stack thus access are much slower. Auto variable can be co (MORE)

Define register transfer language?

A kind of hardware description language (HDL) usedin describing the registers of a computer or digitalelectronic system, and the way in which data is transferredbetween them.

Advantages of register variable?

Registers offer the least possible access time for a value. If you are going to be making a great number of reads or writes to a variable in a short amount of time, it would be very beneficial to use a register for this variable, if possible.

The language like 'c' allows the use of same name for two different variables Is it possible for lexical analyser to distinguish between such variables?

Using the same name for two different variables in languages like C is possible only within two different scopes, such as outside a block and inside a block.... int somevariable; /* outside scope */ { ... int somevariable; /* inside scope */ }. In order for a lexical analyzer to distinguish (MORE)

What are registers in assembly language?

Registers are memory locations on the microprocessor itself (not in main memory). In RISC architectures generally most operations (add, multiply, etc) must take there input from registers and write their output to a register. Since registers are located directly on the microprocessor, they represent (MORE)

What do you mean by a definition of a variable in c LANGUAGE?

Definition of a variable: A variable is a data name that may be used to store a data value. A variable may take different values at different times during execution. Variable names may consist of letters,digits and the underscore(_) character: 1.Must begin with a letter. Some Systems permit unders (MORE)

Where the register variables are stored?

As all the processing is done in the CPU , the idea is that if a variable is going to be used a lot , if possible it should be kept in one of the CPU registers instead of being transferred between the CPU and RAM .

Is type checking on pointer variables stronger in assembly language or in c plus plus?

C++ imposes far greater restrictions on pointer typing than assembly language. There is only a single type of pointer in assembly, which is only "typed" in any sense when dereferenced, and even then only by size. C++ pointer typing takes into account not only the size of the type of the referent, (MORE)

In basic c language structure what is variable?

Variables are named memory locations that may be used to store and retrieve values for use later on in a program. They are like memory locations you have in your brain to remember certain things. Variables may (in general) store a single value at a time, but may be erased with other values (one at a (MORE)

Can a pointer be stored in a register variable?

Yes. int x; register int y; int *p; register int *q; p= &x; /* ok */ q= &x; /* ok */ p= &y; /* BAD */ q= &y; /* BAD */ Here's what it says in the book "The Waite Group's Microsoft C Bible": "You can use the register qualifier only for variables of type int or for pointers (MORE)

What is the difference between normal variable and register variable in c?

In C/C++ when we declare a variable; e.g int var; for this variable (i.e. var) memory is being reserved in RAM (i.e out side processor). If we declare variable like that; register int var2; for this variable memory is being reserved in register of CPU (i.e. withing processor) Bu (MORE)

What are register variables in c?

A register specifier for a variable is a compiler hint that the variable is used often and should be kept in a CPU register. The compiler will treat the variable as automatic, but it will give it preference for staying in a register between sequence points.

What is register variable in c plus plus?

It has no meaning in C++11 as it was deprecated. It exists merely because it existed in C. The purpose of the keyword was to hint to the compiler that the named variable will be heavily used and should therefore be placed in a CPU register rather than allocated memory of its own, thus improving effi (MORE)

Where the variable would be stored in c language?

The Variable will be stored in main memory, if at the time of declaration it is not preceded by any keyword. This is because it will be an auto variable and all the auto variable are stored in main memory. The variable that is stored other than main memory is register variable (stored in register, t (MORE)

What are global variables in c language?

Global variables are named storage locations that are allocated (and possibly initialized) when the program is loaded. Global variables are accessible by name from within any function. In C source, a global is a variable that is declared outside of any function, without an extern or static stora (MORE)

What is variable definition in c language?

variable definition means to declare the variable with its value. for example:- int i=10; this statement is a combination of declaration of integer i and assign its value to it,so it is a definition statement Note: assigning a value is not essential.

How does push work on registers and variables?

The PUSH instruction decrements the stack pointer by the size of the operand and then stores its operand at the memory address pointed to by the stack pointer. This leaves the stack pointer always pointing to the last element pushed onto the stack. The POP instruction reverses the sequence, retri (MORE)

Why do you use clrscr after the declaration of variables in c language?

Most programmers declare variables at the top of a function and place them in descending order of size to minimise wasted memory from alignment. However, there is no specific requirement to clear the screen before processing those variables. In fact, it's best not to clear the screen at all. Ideally (MORE)

What is the use of variables in c language?

Variable is of any Data Type and Data Type can be defined as a type of value that a Variable will hold.............means which type of value you want to store, eg: fractional value (3.5454), whole value (3,76,3,67), character value (a,v,c,f,b,z) etc.......... So The Use the Variable is to store a (MORE)

How is a variable declare in c language?

A variable is declared by declaring its name and type. Once avariable is declared you can use it in expressions, whether toassign a value or use the value. The name is also a reference tothe memory address allocated to the variable, thus you can take theaddress of the name if required.

What is a register variable in c programming?

A register variable is a variable that we wish to allocate in a CPUregister rather than in a memory address (RAM). Register variablesmust be less than or equal in length to the word length of a CPUregister which typically limits their use to integral types andpointers. Typical uses for register vari (MORE)

What is variables in c languages?

Variables are means for location in memory used by a program to store data. The size of that block depends upon the range over which the variable is allowed to vary. For example, on personal computer the size of an integer variable is two bytes, and that of a long integer is four bytes. A variable r (MORE)

When declaring a variable in languages such as c java and c?

In C, C++ and Java, all variables must be declared before they canbe used. A declaration determine's the variable's type and name,nothing more. The type must be visible to the compiler at the pointof declaration in order to determine the amount of memory requireby that type. The type naturally deter (MORE)