register Variables in C

By: Grenfel Emailed: 1646 times Printed: 2113 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

A register declaration advises the compiler that the variable in question will be heavily used. The idea is that register variables are to be placed in machine registers, which may result in smaller and faster programs. But compilers are free to ignore the advice.

The register declaration looks like

   register int  x;
   register char c;
and so on. The register declaration can only be applied to automatic variables and to the formal parameters of a function. In this later case, it looks like
   f(register unsigned m, register long n)
   {
       register int i;
       ...
   }
In practice, there are restrictions on register variables, reflecting the realities of underlying hardware. Only a few variables in each function may be kept in registers, and only certain types are allowed. Excess register declarations are harmless, however, since the word register is ignored for excess or disallowed declarations. And it is not possible to take the address of a register variable, regardless of whether the variable is actually placed in a register. The specific restrictions on number and types of register variables vary from machine to machine.

C Home | All C Tutorials | Latest C Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.



Bookmark and Share

Comments(1)


1. View Comment

Can you provide some more specific application of keyword 'register' ,please?

View Tutorial          By: Rushikesh at 2012-01-15 18:23:36

Your name (required):


Your email(required, will not be shown to the public):


Your sites URL (optional):


Your comments:



More Tutorials by Grenfel
Verifying a Signed JAR File example
Bitwise and Bit Shift Operators example in Java
JavaBeans Basic Concepts
The Differences Between Simple and Classic Tags in JSP
Bitwise Logical Operators in C
DispatchAction in Struts
union example program in C
Comparison operators in JSP
Basics of Structures in C
register Variables in C
Struts and Tiles - Steps to use Struts and Tiles
The if else statement in C
Character Counting sample program in C
Installing JSF
cin.ignore() in C++

More Tutorials in C
Sum of the elements of an array in C
Printing a simple histogram in C
Sorting an integer array in C
Find square and square root for a given number in C
Simple arithmetic calculations in C
Command-line arguments in C
Calculator in C
Passing double value to a function in C
Passing pointer to a function in C
Infix to Prefix And Postfix in C
while, do while and for loops in C
Unicode and UTF-8 in C
Formatting with printf in C
if, if...else and switch statements in C with samples
Statements in C

More Latest News
Most Viewed Articles (in C )
Using memset(), memcpy(), and memmove() in C
UNIX read and write system calls sample program in C
Printing a simple histogram in C
lseek() sample program in C
perror() Function - example program in C
Open, Creat, Close, Unlink system calls sample program in C
Listing Files and Directories sample program in C
Find square and square root for a given number in C
goto and labels in C
Using free() Function in C
Character Arrays in C
File Inclusion in C
Structures and Functions in C
Using Shift Operators in C
assert() Function Example program in C
Most Emailed Articles (in C)
Multi-dimensional Arrays in C (Explained using date conversion program)
Arguments - Call by Value in C
Macro Substitution using #define in C
Formatting with printf in C
Unicode and UTF-8 in C
Character Arrays in C
Pointer Arrays and Pointers to Pointers in C
Open, Creat, Close, Unlink system calls sample program in C
lseek() sample program in C
Sum of the elements of an array in C
The for statement in C
Symbolic Constants using #define in C
Initialization of Variables in C
Pointers vs. Multi-dimensional Arrays in C
Using Bit-field in C