A programmer's calculator for C/C++ expressions. Cast values, shift bits, work with hex and binary, and see the result in four number formats at once.
Open the calculator — runs in your browser with WebAssembly.
The recursive factorial example
evaluates 10! entirely at compile time.
The compact editor is equally useful for masks, shifts, and protocol bytes:
((0xA5 << 8) | 0x5A) ^ 0x0F0F produces the recognizable 0xAA55.
Powered by Clang constexpr, PCalc Express uses C/C++ constant-expression rules, including casts, bitwise operations, character literals, and constexpr-capable C++ lambdas. Choose your language standard in Settings → Advanced.
| Try this | Result |
|---|---|
(0xFF << 8) | 0xA5 |
65445 (0xFFA5) |
(unsigned char)255 |
255, with an 8-bit result type |
static_cast<int>(3.75) |
3 in C++ mode |
0b1010 ^ 0b0011 |
9 |
'A' + 1 |
66 |
7 / 2 / 7.0 / 2 |
3 / 3.5 |
Decimal, hexadecimal, binary, and floating-point results each have a copy button.
Integer width and signedness follow the result type supplied by the evaluator.
Use the control beside Hex to choose byte/word spacing or a 0x prefix.
The Float precision menu offers Auto or 0, 2, 4, 6, 8, or 12 decimal places.
Formatting choices are saved, update the current result without recalculating,
and apply when copying the display.
^ means XOR; shifts require integers. Standard-library headers and functions
are not generally available.
Invoked lambdas can contain local variables, loops, and recursion when permitted
by the selected C++ standard. Top-level declarations and preprocessor directives
are not accepted; results must be numeric constant expressions.
- Enter or = calculates; Ctrl+E focuses the expression.
- Expand the expression editor for multiple lines. Enter inserts a newline while expanded; Ctrl+Enter (or ⌘+Enter) calculates. A newline button is available when using the calculator keypad. Drag the grip below the expanded editor to resize it. Collapse keeps your text and chosen height.
- The keypad inserts at the cursor. ←/→, DEL, and AC handle editing.
- General includes SPACE beside the parentheses. More ▾ opens a centered operator palette with Numbers, Bitwise, Logic, and Math categories.
- Syntax coloring and bracket matching help you read nested expressions.
- Reuse calculations from session history, expand or collapse result units, and switch between light and dark themes from the application menu.
- Settings → Use system keyboard lets you choose the phone keyboard or the calculator keypad. Your choice is saved; physical keyboards remain usable.
- Settings → Theme → E-ink uses black text, white surfaces, outlined keys, and reduced motion for e-readers.
- Screen readers receive named expression, result, keypad, application, and window controls. See the accessibility guide for widget tests and real GTK4/AT-SPI validation.
Clang is the preferred evaluator where available. Optional backends have their own syntax and platform requirements. See the standard-library support tracker for current calculator helpers, missing libc/libc++ APIs, and verification status.
For portable environments and isolated agent branches, start with the task workspace guide: one devcontainer configuration for local Docker, a remote server, or Codespaces.
See the development guide for local builds, tests, screenshots, and GitHub Pages deployment, or Flatpak packaging for Linux installation and packaging details. Keypad changes should follow the calculator keypad design guide.
Inspired by AnalogX PCalc. Built with Flutter and LLVM/Clang, with TinyExpr++ retained as an alternative evaluator.
Licensed under GNU AGPLv3, version 3 only. Dependencies retain their respective licenses.