Difference between LL and LR parser Last Updated : 29 Jul, 2019 Comments Improve Suggest changes Like Article Like Report LL Parser includes both the recursive descent parser and non-recursive descent parser. Its one type uses backtracking while another one uses parsing table. Theses are top down parser. Example: Given grammar is S -> Ac A -> ab where S is start symbol, A is non-terminal and a, b, c are terminals. Input string: abc Parse tree generated by LL parser: LR Parser is one of the bottom up parser which uses parsing table (dynamic programming) to obtain the parse tree form given string using grammar productions. Example: In the above example, parse tree generated by LR parser: Difference between LL and LR parser: LL Parser LR Parser First L of LL is for left to right and second L is for leftmost derivation. L of LR is for left to right and R is for rightmost derivation. It follows the left most derivation. It follows reverse of right most derivation. Using LL parser parser tree is constructed in top down manner. Parser tree is constructed in bottom up manner. In LL parser, non-terminals are expanded. In LR parser, terminals are compressed. Starts with the start symbol(S). Ends with start symbol(S). Ends when stack used becomes empty. Starts with an empty stack. Pre-order traversal of the parse tree. Post-order traversal of the parser tree. Terminal is read after popping out of stack. Terminal is read before pushing into the stack. It may use backtracking or dynamic programming. It uses dynamic programming. LL is easier to write. LR is difficult to write. Example: LL(0), LL(1) Example: LR(0), SLR(1), LALR(1), CLR(1) Comment More infoAdvertise with us Next Article Difference between LL and LR parser P pp_pankaj Follow Improve Article Tags : Compiler Design Similar Reads Difference Between Tokens and Terminals In computer science and programming languages syntax analysis, and parsing tokens and terminals are considered as the basic unit. They are the basic meaningful divisions of input data that are isolated by the lexical analyzer during the first stage of a compilerâs functioning. These tokens are then 4 min read Difference Between Compiler and Interpreter The Compiler and Interpreter, both have similar works to perform. Interpreters and Compilers convert the Source Code (HLL) to Machine Code (understandable by Computer). In general, computer programs exist in High-Level Language that a human being can easily understand. But computers cannot understan 6 min read Difference Between Assembler and Interpreter Humans can only understand source codes written in high-level languages like Python, java, c++, etc, or low-level languages like PHP. On the other hand, computers can only understand machine code written in 0s and 1s. To solve this issue we need a translator that can translate the source code into m 4 min read Difference Between Top Down Parsing and Bottom Up Parsing Parsing is a process in which the syntax of a program is checked by a parser and a parse tree is constructed for the same. There are two main approaches to parsing in compilers: based on them, I have come across two parsing methods namely the top-down parsing and the bottom-up parsing. Both techniqu 5 min read SLR, CLR and LALR Parsers Parsing is a fundamental process in compiler design that helps analyze and validate the syntax of programming languages. It converts a sequence of tokens into a structured format, often represented as a parse tree. Among various parsing techniques, LR parsers are widely used due to their efficiency 8 min read Like