EngFormat-Cpp

C++ based Engineering Notation Formatter

The C++ engineering formatter presented here is partly based on code found on stackoverflow [1] and partly based on the code by Jukka Korpela and David Hoerl as available from the project EngineeringNotationFormatter [2] on GitHub.

Example usage

#include "eng_format.hpp"
#include <iostream>

int main()
{
    std::cout << to_engineering_string( 1234, 3, eng_prefixed, "Pa") << std::endl;
}

Compile and run:

prompt>g++ -Wall -Wextra -I../src -o example1.exe example1.cpp ../src/eng_format.cpp && example1
1.23 kPa

Basic C++ interface

/**
 * convert a double to the specified number of digits in SI (prefix) or
 * exponential notation, optionally followed by a unit.
 */
std::string
to_engineering_string( double value, int digits, bool exponential, std::string unit = "", std::string separator = " " );

/**
 * convert the output of to_engineering_string() into a double.
 */
double
from_engineering_string( std::string text );

/**
 * step a value by the smallest possible increment.
 */
std::string
step_engineering_string( std::string text, int digits, bool exponential, bool increment );

Expanded C++ interface

extern struct eng_prefixed_t {} eng_prefixed;
extern struct eng_exponential_t {} eng_exponential;

const bool eng_increment = true;
const bool eng_decrement = false;

/**
 * convert a double to the specified number of digits in SI (prefix) notation,
 * optionally followed by a unit.
 */
std::string
to_engineering_string( double value, int digits, eng_prefixed_t, std::string unit = "", std::string separator = " " );

/**
 * convert a double to the specified number of digits in exponential notation,
 * optionally followed by a unit.
 */
std::string
to_engineering_string( double value, int digits, eng_exponential_t, std::string unit = "", std::string separator = " " );

/**
 * step a value by the smallest possible increment, using SI notation.
 */
std::string
step_engineering_string( std::string text, int digits, eng_prefixed_t, bool increment );

/**
 * step a value by the smallest possible increment, using exponential notation.
 */
std::string
step_engineering_string( std::string text, int digits, eng_exponential_t, bool increment );

Notes and References

[1] scls. Convert float number to string with engineering notation (with SI prefixe) in Python [closed]. StackOverflow.

[2] David Hoerl. EngineeringNotationFormatter. iOS Project demoing C-based Engineering Notation Formatter.