Unit V: Input/Output and Low-Level Programming

Course: Programming with C
Code: CADSM101

Standard and Formatted Input/Output

C provides a set of library functions for input and output operations, primarily through the stdio.h header file.

• Standard I/O: Includes basic character-based functions and standard stream handling.
• Formatted Output (printf): Allows for controlled printing of various data types using format specifiers (e.g., %d, %f, %s).
• Formatted Input (scanf): Used to read formatted data from the standard input (keyboard).
• Variable Length Arguments: Techniques that allow functions to accept a different number of arguments during different calls.

Data Files and File Access

File handling allows a C program to store data permanently on a storage device.

• Opening and Closing: Files must be opened using fopen() and closed using fclose() to free resources.
• Creating and Processing: Programs can create new files or modify existing ones by reading from or writing to them.
• File Access: Files can be accessed sequentially or randomly using functions like fseek().
• Unformatted Data Files: Handling raw binary data instead of text for efficiency or specific data structures.

Low-Level Programming

C provides unique features that allow programmers to interact closely with computer hardware.

• Register Variables: Using the register keyword to suggest the compiler store a variable in a CPU register for faster access.
• Bitwise Operations: Operators that manipulate individual bits (AND &, OR |, XOR ^, NOT ~, Shifting << >>).
• Bit Fields: Allow the definition of structure members that occupy a specific number of bits, saving memory.
• Enumeration (enum): A user-defined data type consisting of a set of named integer constants.

The C Preprocessor and Macros

The preprocessor is a tool that examines the source code before actual compilation begins.

• Macros: Defined using #define, these allow for symbolic constants or short functional code snippets that are replaced by the preprocessor.
• Conditional Compilation: Using directives like #ifdef or #ifndef to compile specific parts of code based on certain conditions.

Library Functions and Command Line Arguments

• Library Functions: Pre-written functions provided by the C standard library to perform common tasks (e.g., string manipulation, math).
• Command Line Parameters: Arguments passed to the program when it is executed from the terminal, enabling dynamic behavior.