The main difference between syntax analysis and semantic analysis is that syntax analysis takes the tokens generated by the lexical analysis and generates a parse tree while semantic analysis checks whether the parse tree generated by syntax analysis follows the rules of the language.
Generally, a programmer writes the program using a high-level programming language. He can understand these programs, but the computer does not understand these codes. Therefore, it is necessary to convert the source code into machine-understandable machine code. The compiler is the software program that helps to perform this conversion process. The entire compilation process consists of a sequence of phases. The output from one phase becomes the input to the next phase. The first phase of compilation is lexical analysis. It reads the source code character by character and converts it to meaningful lexemes in the form of tokens. Furthermore, the second and third phases are syntax and semantic analysis.
Key Areas Covered
1. What is Syntax Analysis
-Definition, Functionality
2. What is Semantic Analysis
-Definition, Functionality
3. Difference Between Syntax Analysis and Semantic Analysis
-Comparison of key differences
Key Terms
Compiler, Lexical Analysis, Parse Tree, Semantic Analysis, Syntax Analysis
What is Syntax Analysis
Syntax analysis is the second phase of the compilation process. It takes the tokens generated at the lexical analysis phase as input and generates a parse tree (syntax tree) as output. In this phase, the parse checks whether the expressions made by the tokens are syntactically correct or not. Thus, this is also called parsing. Moreover, the parse checks whether the token arrangements are checked against the source code grammar.
What is Semantic Analysis
Semantic analysis is the third phase of the compilation process. It checks whether the parse tree generated by the syntax analysis phase follows the rules of the language. The semantic analyzer keeps track of identifiers, their types and expressions. Finally, the semantic analysis outputs an annotated syntax tree as an output.
Difference Between Syntax Analysis and Semantic Analysis
Definition
Syntax analysis is the process of analyzing a string of symbols either in natural language, computer languages or data structures conforming to the rules of a formal grammar. In contrast, semantic analysis is the process of checking whether the generated parse tree is according to the rules of the programming language.
Handled By
The parser performs syntax analysis while the semantic analyzer performs semantic analysis.
Phase of compilation
Syntax analysis is the second phase of the compilation process, while semantic analysis is the third phase of the compilation process.
Functionality
While syntax analysis takes the tokens as input and generates a parse tree as output, semantic analysis checks whether the parse tree is according to the rules of the language. Thus, their functionality is the main difference between syntax and semantic analysis.
Output
Moreover, syntax analysis generates a parse tree, while semantic analysis generates an annotated syntax tree. Hence, this is another difference between syntax and semantic analysis.
Conclusion
In brief, a compiler is a software program that converts the source code into machine code so that the computer can perform the tasks defined in the program. There are multiple phases in the compilation process. Two of them are syntax analysis and semantic analysis. The main difference between syntax analysis and semantic analysis is that syntax analysis takes the tokens generated by the lexical analysis and generates a parse tree while semantic analysis checks whether the parse tree generated by syntax analysis follows the rules of the language.
References:
1.“Compiler Phases – Javatpoint.” Www.javatpoint.com, Available here.
Image Courtesy:
1.”An ideal multi-language, multi-target compiler” By I, Surachit (CC BY-SA 3.0) via Commons Wikimedia
