From Standard I/O to System I/O
Explore how C programs handle input and output at two levels: the high-level standard I/O using buffered functions and the low-level system I/O with direct kernel calls. Learn the differences in control, portability, and error handling to understand when to use each method effectively for efficient and reliable C programming.
So far in this course, we have used C’s standard input and output functions such as printf(), scanf(), fopen(), fread(), and fprintf(). These functions are convenient, portable, and easy to use. However, they are not the lowest level at which input and output occur.
Underneath the functions declared in <stdio.h>, the operating system provides lower-level system calls that perform the actual data transfer. In this lesson, we examine how standard I/O relates to system I/O and understand the differences in buffering, error handling, and control.
Two layers of I/O in C
C programs typically interact with I/O at two different levels:
Standard I/O (stdio library) is the high-level, portable interface provided by C. It includes functions like
printf(),scanf(),fopen(), andfgets(). It is buffered, meaning data is temporarily stored in memory before being sent to the operating system, which improves ...