Redeclaration of global variable in C

2

Consider the below two programs:

// Program 1
int main()
{
   int x;
   int x = 5;
   printf("%d", x);
   return 0; 
}

Output in C:

redeclaration of ‘x’ with no linkage
// Program 2
int x;
int x = 5;

int main()
{
   printf("%d", x);
   return 0; 
}

Output in C:

5

In C, the first program fails in compilation, but second program works fine. In C++, both programs fail in compilation.


C allows a global variable to be declared again when first declaration doesn’t initialize the variable.

The below program fails in both C also as the global variable is initialized in first declaration itself.

int x = 5;
int x = 10;

int main()
{
   printf("%d", x);
   return 0;
}

Output:

 error: redefinition of ‘x’

This article is contributed Abhay Rathi. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above

GATE CS Corner    Company Wise Coding Practice

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