Why 'fputc' use an INT as its parameter instead of CHAR?

Question

standard C lib:

int fputc(int c , FILE *stream);

And such behaviors occured many times, e.g:

    int putc(int c, FILE *str         


        

Answer 1

No char parameters in K&R C

One reason is that in early versions¹ of C there were no char parameters.

Yes, you could declare a parameter as char or float but it was considered int or double. Therefore, it would have, then, been somewhat misleading to document an interface as taking a char argument.

I believe this is still true today for functions declared without prototypes, in order for it to be possible to interoperate with older code.

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^{1. Early, but still widespread. C was a quick success and became the first (and still, mostly, the only) widely successful systems programming language.}