extern in c - codingtube

extern in c is part of External Storage Class. extern keyword is used in c to declare external variable outside the function

Before going to know extern first know the External Storage Class

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External Storage Class

External variables are declared outside all functions, yet are available to all functions that care to use them

int x = 21 ; 
main( ) 
{ 
 extern int y ; 
 printf ( "\n%d %d", x, y ) ; 
} 
int y = 31 ;

In the above example extern int y has been initialize outside the function