Arduino library to help formatting integers for printing as currency.

Experimental

The currency library contains a number of functions that help to print integers as currency.

The currency functions assume you do the currency math in integer units. For dollars and euro's this would be cents. For numbers with more decimals it is a smaller unit.

Using integers makes addition, subtraction and multiplication of currency exact.

Choosing int32_t as 'base' also means that there is a limit in terms of minimum and maximum values. When large amounts are needed one can use the currency64() or one of its derived formatters as this is based upon int64_t numbers.

The 0.2.0 version added wrapper functions in the form of a TLA (Three Letter Acronym). The TLA's are international used acronyms for currency e.g. CNY(value) or GBP(value).

There is a relation with the printHelpers class - https://github.com/RobTillaart/printHelpers When this currency library has matured it might be merged with printHelpers.

As always feedback (or ideas for extensions) are welcome.

The library 0.1.x had experimental wrappers for float/double values. Testing showed the limits of float => seven significant digits explicitly. As that caused the converted string to be incorrect (thus useless) this part of the API is deprecated.

Not all symbol codes work on all platforms, so you need to test for your platform.

More see e.g. https://www.webnots.com/alt-code-shortcuts-for-currency-symbols/

• https://github.com/RobTillaart/printHelpers
• https://www.easymarkets.com/eu/learn-centre/discover-trading/currency-acronyms-and-abbreviations/

#include "currency.h"

The following functions are implemented:

• char * currency(int32_t value, uint8_t decimals, char decimalSeparator, char thousandSeparator, char symbol)
• char * currency64(int64_t value, uint8_t decimals, char decimalSeparator, char thousandSeparator, char symbol)

• char * bitcoin(int32_t value)
• char * dollar(int32_t value)
• char * euro(int32_t value)
• char * pound(int32_t value)
• char * roubles(int32_t value)
• char * yen(int32_t value)
• char * yuan(int32_t value)

• char * bitcoin64(int64_t value)
• char * dollar64(int64_t value)
• char * euro64(int64_t value)
• char * pound64(int64_t value)
• char * roubles64(int64_t value)
• char * yen64(int64_t value)
• char * yuan64(int64_t value)

• char * BTC(int32_t value)
• char * USD(int32_t value)
• char * EUR(int32_t value)
• char * GBP(int32_t value)
• char * RUB(int32_t value)
• char * JPY(int32_t value)
• char * CNY(int32_t value)

• char * BTC64(int32_t value)
• char * USD64(int32_t value)
• char * EUR64(int32_t value)
• char * GBP64(int32_t value)
• char * RUB64(int32_t value)
• char * JPY64(int32_t value)
• char * CNY64(int32_t value)

Deprecated, has serious limitations, therefore commented in the library.

All assumes 2 decimals except bitcoin which has 6. The accuracy of a float is just 7 digits. On some platforms (e.g. UNO R3) float == double so one gets errors.

• char * bitcoinf(double value)
• char * dollarf(double value)
• char * eurof(double value)
• char * poundf(double value)
• char * roublesf(double value)
• char * yenf(double value)
• char * yuanf(double value)

See examples.

Performance is hard to optimize. Most time is spend in splitting individual digits (div / mod 10). The divmod10() function from my fast_math library might be an option.

• update documentation.

• investigate a better double/float API
• investigate impact divmod10() for int32 and int64.

• add more TLA wrapper functions
• consider .h library only as codebase is rather small?

• currency conversion
  • ratios change daily (or faster)
  • intern in pecunia

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Thank you,