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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 converted to register by using register keyword before it. It has platform specific limitation. Register variable will work only if free registers are available to hold the variable for a function scope. In case of Microprocessor or microcontrollers having very less number of general purpose registers will never take register variable even if we declare it as register.
Can we declare register variable as global?
Globals and statics are both allocated in static memory. Locals are allocated on the stack.
Is a global variable a non-local variable?
True, a variable cannot be both global and local. But if a global and a local variable share the same name, the local one will hide the global.
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 class register?
Register storage class is a compiler hint that the variable will be often used, and that it should generate code, if it can, to keep the variable's value in a register.
Describe about storage allocation and scope of global extern static local and register variables?
Global Varible: The variable which is declared as "Global" one : having the preveleges to use and access that variable in any class and object( means any where in the program) just like PUBLIC keyword in OOPS concepts. Static Variable : If we declare a variable as Static , then it wont have the permission to access that variable through out the program and u have to use it inside the class or object which u declared itself. All the Best Annapurna
What happens if you try to find address of register variable?
Either you get a compiler error. Or you get a compiler warning, and the variable won't be stored in register.
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) But register variables are discouraged because processor has to work with registers..... Note: strictly speaking, storage class 'register' means: dear compiler, you might optimize this variable into register, as I won't ever request its address. But of course, it's up to you to decide.
What is the difference between a static variable a global variable and a local variable?
A static variable is a variable allocated in static storage. A local variable is a variable declared inside a function. A global variable is a variable declared outside of any class or function. Note that local variables and global variables can both be allocated in static storage.
What are the functions of a storage class?
There are four storage class specifiers in C and C++. These are - 1. auto : The storage specifier auto refers to automatic variable declaration. The life of an automatic variable is the time during which its parent function is running. The scope of an auto variable is the function scope. They can be accessed only from their parent functions. Syntax : auto int a; 2. register : A register variable has all the characteristics of an auto variable. The only difference is that auto variable uses the main memory to store data and register uses the CPU registers. 3. extern : This storage specifier is used to declare a global variable. The life of these variables is the time during which the program runs.
Which register is used as a local variable?
accumulator
How can you declare global and local variable in pseudocode?
A local variable is a variable declared inside a construct, such as a class or function, while a global variable is a variable declared outside of any construct.
