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C: Locally extern variable is resulting in error?

+4 votes
314 views

case:1

int main(void)
{
  extern int var = 0;
  var = 10;
  return 0;
}

case:2

#include<stdio.h>
extern int a;
int main()
{
 extern int a;
 int a=34;
 printf("%d",a);
 return 0;
}

In both cases it's error why so? Curious to know exactly how declaration of variable with extern differ locally and globally ?

More informative answer is most welcome.

posted Jan 24, 2014 by Atiqur Rahman

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When you declare a symbol extern, you are telling the compiler to link all occurrences of this value into the same symbol.

Any occurrences of extern int a; in your program would link to the externally defined a.
commented Jan 24, 2014 by Salil Agrawal

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