What is the use of the extern keyword in c?

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Dude, after researches I understood that extern serves to indicate that a variable has already been defined in another part of the program as a whole. For example, if you divide a giant code into 2 parts. You should indicate to the compiler that you are using these variables in a block (file 2) but they have been initialized in another block (code 1).

for example:

Code 1:

int count;
float sum;
int main(void)
{
    ...
    return 0;
}

Code 2:

extern int count;
extern float sum;
int RetornaCount(void)
{
    return count;
}

Here’s a link that explains much better than me: http://mtm.ufsc.br/~Azeredo/cursoC/aulas/ca20.html

I hope I’ve helped.

  • Correct. And one of the utilities of the files . h is precisely to contain the statements of variables with extern, to avoid errors of copying and pasting.

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