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SCOPE OF VARIABLES IN C

MUHAMMED THANVEER.Mkutubmadar@gmail.comwww.facebook.com/usernametwitter.com/usernamein.linkedin.com/in/profilename9526960445

WHAT IS VARIABLE

A variable is nothing but a name given to a storage area that our programs can manipulate. Each variable in C has a specific type, which determines the size and layout of the variable's memory; the range of values that can be stored within that memory; and the set of operations that can be applied to the variable.

BASIC VARIABLE TYPES

Type Description

charTypically a single octet(one byte). This is an integer type.

int The most natural size of integer for the machine.

float A single-precision floating point value.

double A double-precision floating point value.

void Represents the absence of type.

Variable ScopeAn Objective-C program will consist of code divided up into functions, classes and code structures (such as do .. while and for loops). Invariably a typical program will make extensive use of variables to store and manipulate data. Once a variable has been declared it may or may not be accessible to other sections of the program code. This accessibility depends on where and how the variable was declared and where the code is that needs to access it. This is known as variable scope

Local VariablesVariables that are declared inside a function or block are called local variablesThey can be used only by statements that are inside that function or block of code. Local variables are not known to functions outside their own.

Following is the example using local variables.

Here all the variables a, b and c are local to main() function.

#include <stdio.h> int main () { /* local variable declaration */ int a, b; int c; /* actual initialization */ a = 10; b = 20; c = a + b; printf ("value of a = %d, b = %d and c = %d\n", a, b, c); return 0; }

Global Variables

Global variables are defined outside of a function, usually on top of the program. The global variables will hold their value throughout the lifetime of your program and they can be accessed inside any of the functions defined for the program.A global variable can be accessed by any function. That is, a global variable is available for use throughout your entire program after its declaration

o Example using global and local variables

#include <stdio.h> /* global variable declaration */ int g; int main () { /* local variable declaration */ int a, b; /* actual initialization */ a = 10; b = 20; g = a + b; printf ("value of a = %d, b = %d and g = %d\n", a, b, g); return 0; }

A program can have same name for local and global variables but value of local variable inside a function will take preference. Following is an example:

#include <stdio.h> /* global variable declaration */ int g = 20; int main () { /* local variable declaration */ int g = 10; printf ("value of g = %d\n", g); return 0; } When the above code is compiled and executed, it produces the following result:value of g = 10

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