How does scanf() work inside the OS?

Question

I\'ve been wondering how scanf()/printf() actually works in the hardware and OS levels. Where does the data flow and what exactly is the OS doing around these times? What calls

Answer 1

scanf , printf etc internally all these types of functions can't be directly written in c/c++ language. internally they all are written in assembly language by the use of keword "asm", any thing written with keyword "asm" are directly introduced to object file irrespective of compilation (not changed even after compilation), and in assembly language we have got predefined codes which can implement all these functions ...... so in short SCANF PRINTF etc ALL ARE WRITTEN IN ASSEMBLY LANGUAGE INTERNALLY. YOU CAN DESIGN YOUR OWN INPUT FUNCTION USING KEYWORD "ASM".