in C51, the default printf() is used for serial comm., depends on putchar.c now, i'm trying to modify it(putchar.c) for my 8-bit LCD.
the question is, can putchar.c or printf() be used on both, serial comm. and 8-bit LCD, at same time (at the same main program)?
nb: i want to display floating point, that's why i'm trying to use printf()
1) Yes, you can write code that sends the data to multiple destinations. It's just up to you to implement the back-end code that takes care of the resulting characters and distributes them where you want them.
2) Alas, I don't think Keil have fcvt() or ecvt() which would have been alternatives to printf()/sprintf(). But it is often possible to work with fixed-point arithmetic instead of floating point with very good results.