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What is the .LEX File Extension?

.LEX File Extension Description:

The Lexical Analyzer Generator, a program generator designed for lexical processing of character input streams, uses The LEX file extension. Through LEX, an input stream is read and can even specify the output source code and lexical analyzer with the lexer implemented in the programming language of C.

The LEX program and the C language are tightly coupled. Thus, files with the .lex file extension, which passes through the LEX utility, produce output files in the C language. These files are then compiled in order to produce an executable version of the lexical analyzer. Though these files are known to be proprietary files of the LEX software, versions of LEX based on the original AT&T code are available as part of systems of OpenSolaris and Plan9.

The structure of the file with the .lex file extension is divided into three sections such as the definition, rules, and C code sections and is divided by lines which contain merely two percentage signs. The so-called definition section of this file is actually the place where macros are defined and where the header files written in C are imported.

The most important section of the file with the .lex file extension is the rules section because it associates patterns with C statements. Patterns are simply regular expressions, which are the basis of how LEX operates. Once the lexer detects some text inside the input that matches any given pattern, LEX executes the associated C code.

The C code section contains C statements and functions that are copied word for word to the generated source file. They contain a code called in the rules section of the files with the .lex file extension. It is more suitable to store the C code in a different file in huge programs and link it in at compile time.

Files with the .lex file extension and files with the .yacc file extension are commonly used together. This is because the files with the .yacc file extension uses formal grammar in order to parse a regarded input stream. This is actually something that files with the .lex file extension can never do with the use of plain regular expressions. On the other hand, files with the .yacc file extension cannot read from simple input stream and require a series of tokens that only files with the .lex file extension can provide.

Author: Eric E. Schmidt
Author URL:
Related Applications: Lexical Analyzer Generator, C Programming Language
Common Path: N/A


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Do you have errors with .LEX files?

The Common Cause of .LEX files Errors to Occur:

A common and likely cause for .LEX files errors is corruption in the Windows registry - fixing is necessary to avoid more corruption in other software and/or devices. Having these errors puts your PC in danger for fatal crashes, blue screen errors as well as hardware failure.

What are the Symptoms of .LEX files Errors?

Common symptoms from .LEX files errors include slower system speed, extended program load times, failure saving documents, excessive suspensions in software functions, software closing without an error, input freezing and software crash.

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