A compiler is a computer program that translates computer code written in one programming language into another language. The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program. Compilers are an essential part of software development, as they allow developers to write programs in high-level languages that humans can understand, but then convert that high-level language into a form that only a machine can read.
Compilers vary in the methods they use for analyzing and converting source code to output code. Despite their differences, they typically carry out the following steps:
- Lexical analysis: The compiler splits the source code into lexemes, which are individual code fragments that represent specific patterns in the code. The lexemes are then tokenized in preparation for syntax and semantic analyses.
- Syntax analysis: The compiler checks the syntax of the source code to ensure that it conforms to the rules of the programming language.
- Semantic analysis: The compiler checks the meaning of the source code to ensure that it is semantically correct.
- Code generation: The compiler generates the output code in the target language.
- Optimization: The compiler optimizes the output code to make it more efficient.
Compilers are often confused with interpreters, which execute source code line-by-line without compiling it into machine-readable code. However, compilers are preferred over interpreters because they catch syntax and semantic errors before running the code, which saves time and prevents crashes. Compilers also optimize the code for efficient execution and produce faster, more compact programs.
