information technology fundamentals notes

Any language’s grammar consists of the rues which govern the languages use.
Any language, whether natural or artificial has lexemes (symbols) and a grammar. Example : void, ;
Semantics: what do the lexemes mean?
Statically typed languages determine the data types of variables during compilation and don’t allow them to change.
Dynamically typed languages determine the data type at run time by looking at how the variable is being used type safe compilation, written in a language, goes to compiler, produces the program into machine code, creates a compiled version.
Compilation, protects intellectual property,
Interpretation, takes a program written in a high-level language, read a line, translates the line into machine code, send translated line to the computer, repeat until finish.
Interpretation, can run on multiple platforms
Just in time, code is written in high level language, each time program runs compiles the program into machine code, after execution compiled version is ‘destroyed’
Compiled- interpreter, high-level language is compiled to an intermediate language, intermediate language version is distributed, code is then interpreted
Compiled-compiled, high-level language is compiled to intermediate language, this version is then distributed, the code is recompiled into machine code when run
Translating from source code to machine code is usu the lexical analyser reads code and turns it into tokens lexers usually to stages, scanning, evaluation scanning read source code and identify the tokens evaluator native compilers translate source code in binaries only for the hardware platform on which they run cross compilers run on one hardware platform but produces binaries for a different platform one pass compilers look through the source code only once, whereas multi-pass compilers look through the source more than once, usually a few times.
One pass faster
Multi-pass slower but more efficient code