Calc.exe is now open source; there’s surprising depth in its ancient code (2019)

• calculator

  81 28,837 7.2 C++

  Windows Calculator: A simple yet powerful calculator that ships with Windows

  

• excalc

  1 1 0.0 Pascal

  vestris inc. expression calculator, circa 96'

PSA: Here's another, much more feature-rich calculator called Expression Calculator (or Global Calculator sold in Germany in 1997), written in Delphi - https://github.com/dblock/excalc, full source code and a working executable that still runs on any version of Windows.

• InfluxDB

  www.influxdata.com sponsored

  Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.

  

• libqalculate

  55 1,635 8.7 C++

  Qalculate! library and CLI

  

Check out Qalculate![1] for an application for a program that does what you specify and much more (though obviously not as much as WA).

1: http://qalculate.github.io/

• calculator-specs

  1 55 0.0

  Spec repository for Windows Calculator (https://github.com/Microsoft/calculator)

  

It works like you say in standard mode by design because it's trying to match the behavior of older desk calculators that worked that way. In scientific mode it respects order of operations.

There's a proposal to change the UI to make this clearer: https://github.com/microsoft/calculator-specs/blob/247bbb50d...

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