Reference
Cheat sheets
5 fast-scanning syntax references, one per language: variables, strings, collections, control flow, functions, and error handling, all in one page you can search with Ctrl/Cmd+F.
A cheat sheet is not a tutorial. It is for the syntax you have already learned once and cannot quite remember the shape of. Try a snippet in the playground, compare the shown output and adapt it to the code you are writing.
C cheat sheet
A scannable C reference covering the program skeleton, printf and scanf format specifiers, types and sizeof, operators, control flow, functions, arrays, strings and string.h, pointers, malloc and free, structs, enums and the preprocessor.
JavaScript cheat sheet
A scannable JavaScript reference covering variables, template literals, string and array methods, objects, destructuring, control flow, functions, arrow functions, and common built-ins.
Python cheat sheet
A scannable Python 3 reference covering variables, f-strings, string methods, lists, dicts, sets, tuples, comprehensions, control flow, functions, built-ins, exceptions, and file handling.
SQL cheat sheet
A scannable SQL reference covering SELECT and WHERE, sorting and limiting, aggregates and GROUP BY, joins, subqueries and CTEs, window functions, INSERT, UPDATE and DELETE, transactions, constraints, and the SQLite-specific behaviour behind each one.
TypeScript cheat sheet
A scannable TypeScript reference covering basic types, interfaces and type aliases, arrays and tuples, functions, union and literal types, generics, enums, type narrowing, and the built-in utility types.
Learning from scratch instead?
Start with the free exercise paths — a cheat sheet only helps once the idea is already familiar. Once you know what you are looking for, try it yourself in a playground.
Questions about the cheat sheets
- How is a cheat sheet different from the lessons?
- A lesson explains an idea the first time you meet it, with the reasoning spelled out. A cheat sheet skips the reasoning and just shows the syntax, grouped so the common cases sort near the top — it is for recalling something you already understood once, not learning it from scratch.
- Are the code snippets actually correct?
- The snippets show language syntax and expected output. Try a runnable example in the matching playground, or check it with the interpreter/compiler version you use. Runtime checks and tested examples cover specific cases; they are not a guarantee that every snippet has been executed in every environment. Report an output mismatch through Contact.
- Why don't all languages have a cheat sheet yet?
- A useful cheat sheet needs selected syntax, explanations and examples that can be checked, so coverage is added language by language. The available sheets are linked from the cheat-sheet hub; there is no promised release date for the remaining languages.