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What are the local and global scope rules in C language?
Global scope
Global scope specifies that variables defined outside the block are visible up to end of the program.
Example
#include<stdio.h>
int c= 30; /* global area */
main (){
int a = 10;
printf (“a=%d, c=%d” a,c);
fun ();
}
fun (){
printf (“c=%d”,c);
}Output
a =10, c = 30 c = 30
Local scope
Local scope specifies that variables defined within the block are visible only in that block and invisible outside the block.
Variables declared in a block or function (local) are accessible within that block and does not exist outside it.
Example
#include<stdio.h>
main (){
int i = 1;// local scope
printf ("%d",i);
}
{
int j=2; //local scope
printf("%d",j);
}
}Output
1 2
Even if the variables are redeclared in their respective blocks and with the same name, they are considered differently.
Example
#include<stdio.h>
main (){
{
int i = 1; //variable with same name
printf ("%d",i);
}
{
int i =2; // variable with same name
printf ("%d",i);
}
}Output
1 2
The redeclaration of variables within the blocks bearing the same names as those in the outer block masks the outer block variables while executing the inner blocks.
Example
#include<stdio.h>
main (){
int i = 1;{
int i = 2;
printf (“%d”,i);
}
}Output
2
Variables declared outside the inner blocks are accessible to the nested blocks, provided these variable are not declared within the inner block.
Example
#include<stdio.h>
main (){
int i = 1;{
int j = 2;
printf ("%d",j);
printf ("%d",i);
}
}Output
2 1
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