ZAK's VB.NET Playground
Visual Basic .NET console programs, compiled by Microsoft's own compiler and run inside your browser — nothing to install, nothing sent to a server. Put what Console.ReadLine() should read in the input box, press Run and get the output, any files it wrote, the error with its line number and a line-by-line trace table. The Examples mirror the Python Playground; switch the toggle to compare languages.
VB.NET example library
72 programs — the same categories as the pseudocode and Python libraries, written the way Paper 4 expects them.
Basics & data types 8
Variables, constants, INPUT/OUTPUT, arithmetic, DIV/MOD, conversions
Selection 5
IF/ELSE, nested IF, CASE with lists and ranges, Boolean conditions
Iteration 6
FOR, WHILE, REPEAT, nested loops, totalling, counting, max/min
String handling 5
LENGTH, SUBSTRING/MID, UCASE/LCASE, ASC/CHR, reversing, palindromes, ciphers
Arrays 5
1D and 2D arrays, parallel arrays, whole-array copy, frequency counts
Procedures & functions 5
Parameters, RETURN, BYREF vs BYVAL, scope, stepwise refinement
Validation, testing & exceptions 7
Range, length, type, format and check-digit checks; verification; test data; trace tables; TRY … EXCEPT
Searching 3
Linear search, binary search (iterative and recursive), comparing efficiency
Sorting 3
Bubble sort (with and without a flag), insertion sort, sorting strings and parallel arrays
File handling 4
Text files (READ/WRITE/APPEND, EOF), delimited records, random-access files
Records & user-defined types 3
TYPE…ENDTYPE records, arrays of records, enumerated, pointer and set types, DATE
Stacks, queues, lists & trees 5
Stack, linear and circular queue, linked list, binary search tree, hash table, dictionary
Recursion 2
Base and general cases, winding/unwinding, factorial, Fibonacci, GCD, Hanoi
Object-oriented programming 5
Classes, constructors, encapsulation, inheritance, polymorphism, containment
Theory in code 3
Number bases, two's complement, parity, logic gates, adders, FDE cycle, compression, floating point, RPN, graphs
Exam-style tasks 3
Complete scenario programs in the style of 2210 Section B, 9618 Paper 2 and Paper 4
How the VB.NET Playground works
- It is Microsoft's VB.NET compiler (Roslyn) running on .NET in WebAssembly, so the compile errors are the ones Visual Studio shows — each with a plain-English hint — and the program runs on the real .NET libraries.
- Like a new Visual Studio console app: Module Module1 with Sub Main(), Option Explicit On, Option Strict Off, Option Infer On, and the usual Imports (System, System.Collections.Generic, Microsoft.VisualBasic …) already there.
- Input: each Console.ReadLine() reads the next line of the input box, echoed like a console window.
- Files (StreamWriter, StreamReader, File.ReadAllLines …) live in a folder that starts empty on every run; whatever the program writes is shown under the output.
- Run-time errors show the .NET exception (IndexOutOfRangeException, FormatException, OverflowException …) with the line it happened on and the call stack.
- Trace table: every change to a local variable, line by line, including inside Subs, Functions and recursion.
- Infinite loops stop after 8 seconds, with the line the program was on. Windows-only parts (Windows Forms, MsgBox, InputBox) are not available; Console.ReadKey() returns straight away and console colours are ignored.
- First use downloads about 7 MB (cached afterwards).
