top button
Flag Notify
    Connect to us
      Site Registration

Site Registration

C: Locally extern variable is resulting in error?

+4 votes
407 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

Looking for an answer?  Promote on:
Facebook Share Button Twitter Share Button LinkedIn Share Button
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

Similar Questions
+4 votes
C: Why redefining of variable is not an error? 
#include<stdio.h>
int var;
int var;
int var;

int main(void) { 
  printf("%d \n",var); 
  return 0;
}
+2 votes
C: Changing value in Union resulting in error? 
typedef union
{
    int integer;
    char* string;
} Value;

main()
{
  Value v = { 1 };
  v = { 2 }; // getting the error on this 
}
+2 votes
C: Is constant variable initialized at the compile time?

I assume that constant must be initialized to a constant value at compile time, but following code the return value of ge_const() is assigned to x which will be collected at run time. So this must cause an error but I am getting the output as 50. Can someone clarify the detail?

main()
{
    const int x = get_const();
    printf("%d", x);
}
int get_const()
{
    return 50;
}
+1 vote
C: When a programmer or designer decides to have volatile variable in code ?

In large product based companies LLD is written by senior team members and developers write the code.
Does the senior team member decide what data type they should use in advance ? If yes then what things derives type of data for example. How they decide a variable should be declared as volatile ? and what would be advantage of having a variable volatile and what could be the problem if it is taken without the volatile ?

...