JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III COMPILER DESIGN Previous Question Paper (February - 2023 - R16)

A linker is a system program that takes one or more object files generated by a compiler or assembler and combines them into a single executable file by resolving references to external symbols and library functions. A loader is a part of the operating system that takes the executable file from the disk, places it into the main memory (RAM), and prepares it for execution by setting up the necessary registers and memory addresses.

A regular expression is a formal notation used to define and represent the set of strings that constitute a regular language. It provides a declarative way to describe patterns in strings, which are essential for specifying the lexical structure of programming languages, such as identifiers, constants, and keywords.

Regular expressions are constructed using three fundamental operations:

• Union: The union of two regular expressions r and s, denoted as r|s, represents the set of strings in either r or s.
• Concatenation: The concatenation of r and s, denoted as rs, represents the set of strings formed by taking a string from r followed by a string from s.
• Kleene Closure: The closure of r, denoted as r*, represents the set of strings formed by concatenating r zero or more times.

These expressions serve as the input for lexical analyzers, which use them to generate finite automata that perform pattern matching during the scanning phase of compilation.