# Microsoft Small Basic

Microsoft Small Basic is a programming language, interpreter and associated IDE. Microsoft's simplified variant of BASIC, it is designed to help students who have learnt visual programming languages such as Scratch learn text-based programming. The associated IDE provides a simplified programming environment with functionality such as syntax highlighting, intelligent code completion, and in-editor documentation access. The language has only 14 keywords.

## History

| Version | Release date |
| Old version, no longer maintained: v0.1 | October 23, 2008 |
| Old version, no longer maintained: v0.2 | December 17, 2008 |
| Old version, no longer maintained: v0.3 | February 10, 2009 |
| Old version, no longer maintained: v0.4 | April 14, 2009 |
| Old version, no longer maintained: v0.5 | June 16, 2009 |
| Old version, no longer maintained: v0.6 | August 19, 2009 |
| Old version, no longer maintained: v0.7 | October 23, 2009 |
| Old version, no longer maintained: v0.8 | February 4, 2010 |
| Old version, no longer maintained: v0.9 | June 11, 2010 |
| Old version, no longer maintained: v0.91 | November 17, 2010 |
| Old version, no longer maintained: v0.95 | February 8, 2011 |
| Old version, yet still maintained: v1.0 | July 12, 2011 |
| Old version, no longer maintained: v1.1 | March 27, 2015 |
| Current stable version: v1.2 | October 1, 2015 |
| Legend:Old version, not maintainedOld version, still maintainedLatest versionLatest preview versionFuture releaseLegend:Old versionOld version, still maintainedLatest versionLatest preview versionFuture release ||
Microsoft announced Small Basic in October 2008, and released the first stable version for distribution on July 12, 2011, on a Microsoft Developer Network (MSDN) website, together with a teaching curriculum and an introductory guide. Between announcement and stable release, a number of Community Technology Preview (CTP) releases were made.
On March 27, 2015, Microsoft released Small Basic version 1.1, which fixed a bug and upgraded the targeted .NET Framework version from version 3.5 to version 4.5, making it the first version incompatible with Windows XP.
Microsoft released Small Basic version 1.2 on October 1, 2015. Version 1.2 was the first update after a four-year hiatus to introduce new features to Small Basic. The update added classes for working with Microsoft's Kinect motion sensors, increased the number of languages supported by the included Dictionary object, and fixed a number of bugs.
On February 19, 2019, Microsoft announced Small Basic Online (SBO). It is open source software released under MIT License on GitHub.

## Language

In Small Basic, one writes the illustrative "Hello, World!" program as follows:
Microsoft Small Basic is Turing complete. It supports conditional branching, loop structures, and subroutines for event handling. Variables are weakly typed and dynamic with no scoping rules.

### Conditional branching

The following example demonstrates conditional branching. It ask the user for Celsius or Fahrenheit and then comments on the answer in the appropriate temperature unit.
Small Basic does not support an inline If statement as does Visual Basic, for example:

### Looping

This example demonstrates a loop. Starting from one and ending with ten, it multiplies each number by four and displays the result of the multiplication.
While loops are also supported, and the demonstrated For loop can be augmented through the use of the Step keyword. The Step keyword is used in setting the value by which the counter variable, i, is incremented each iteration.

### Data types

Small Basic supports basic data types, like strings, integers and decimals, and will readily convert one type to another as required by the situation. In the example, both the Read and ReadNumber methods read a string from the command line, but ReadNumber rejects any non-numeric characters. This allows the string to be converted to a numeric type and treated as a number rather than a string by the + operator.
As Small Basic will readily convert among data types, numbers can be manipulated as strings and numeric strings as numbers. This is demonstrated through the second example.
In the second example, both strings are treated as numbers and added together, producing the output 3100. To concatenate the two values, producing the output 1003000, it is necessary to use the Text.Append(text1, text2) method.

## Libraries
### Standard library

The Small Basic standard library includes basic classes for mathematics, string handling, and input/output, as well as more exotic classes that are intended to make using the language more fun for learners. Examples of these include a Turtle graphics class, a class for retrieving photos from Flickr, and classes for interacting with Microsoft Kinect sensors.
To make the classes easier to use for learners, they have been simplified. This simplification is demonstrated through the code used to retrieve a random mountain-themed image from Flickr:

#### Turtle graphics

Small Basic includes a "Turtle" graphics library that borrows from the Logo family of programming languages. For example, to draw a square using the turtle, the turtle is moved forward by a given number of pixels and rotated 90 degrees in a given direction. This action is then repeated four times to draw the four sides of the square.
More complex drawings are possible by altering the turning angle of the turtle and the number of iterations of the loop. For example, one can draw a hexagon by setting the turn angle to 60 degrees and the number of iterations to six.

### Third-party libraries

Small Basic allows the use of third-party libraries. These libraries must be written in a CLR-compatible language, and the compiled binaries must target a compatible .NET Framework version. The classes provided by the library are required to be static, flagged with a specific attribute, and must use a specific data type.
An example of a class to be used in Small Basic is provided below, written in C#.
If available, the Small Basic development environment will display documentation for third-party libraries. The development environment accepts documentation in the form of an XML file, which can be automatically generated from source code comments by tools such as Microsoft Visual Studio and MonoDevelop.