What is a symbol table in a compiler, and how is it used?

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Krishnapriya Rajeev · Answer

In a compiler, a symbol table is a data structure that keeps track of the information about symbols (such as variables, functions, classes, etc.) used in the source code of a program being compiled. The symbol table is an essential part of the compiler's front end, which is responsible for processing the source code.

The symbol table is used in various phases of the compiler to perform different tasks. Here are some of the phases where the symbol table is used:

Lexical Analysis: Creates new table entries in the symbol table for tokens.
Syntax Analysis: Adds the information about attribute type, scope, dimension, line of reference, and use to the symbol table.
Semantic Analysis: Uses the data in the symbol table to check the correctness of the semantics of expressions and assignments, and updates the table accordingly.
Intermediate Code Generation: Refers to the symbol table to determine the amount and type of run-time allocated, and helps add temporary variable information to the table.
Code Optimization: Uses the symbol table's data to perform machine-dependent optimization.
Target Code Generation: Utilizes the address information of identifiers present in the symbol table to create code.

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What is a symbol table in a compiler, and how is it used?

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