c - putc needs stdout, vs puts

Question

C history question here. Why does the C function putc require a second parameter like

putc( 'c', stdout ) ;

While puts is oh so more convenient

puts( "a string" ) ;

There is a function in msvc++

putchar( 'c' ) ;

Which works the way one might expect putc to work. I thought the second parameter of putc was to be able to direct putc to a file, but there is a function fputc for that.

Answer 1

int putc ( int character, FILE * stream );

Writes a character to the stream and advances the position indicator.
So it is a more generic function than putchar
Other functions can be based on this e.g.

#define putchar(c) putc((c),stdout)  

According to Kernighan's book putc is equivalent with fputc but putc could be implemented as a macro and putc may have to evaluate its stream argument more than once.
I have read that supposedly that both exist for backward compatibility, but not sure if this is valid