c-resources/CPlusPlus20ForProgrammers-m.../examples/libraries/BigNumber/README.md

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# BigNumber
![BigNumber build](https://travis-ci.org/Limeoats/BigNumber.svg?branch=master)
[![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://github.com/Limeoats/BigNumber/blob/master/LICENSE.md)
BigNumber is a C++ class that allows for the creation and computation of arbitrary-length
integers.
The maximum possible length of a BigNumber is `std::string::max_size`.
## Installation
To add BigNumber to your C++ project, you can download the `bin` folder from this repository, which
contains the library and include files.
Then, simply include the header file in whichever file you need a BigNumber and link to the library file.
`#include "bignumber.h"`
## Usage
### `BigNumber(string)`
You can also use the `=` operator to set a BigNumber equal to an existing BigNumber, a number, or
a string of numbers.
Examples:
BigNumber b("5"); //BigNumber b is created with value 5.
BigNumber c("-20"); //BigNumber c is created with value -20.
BigNumber d("0"); //BigNumber d is created with value 0.
BigNumber e = b; //BigNumber e is created with value 5.
BigNumber f = 30; //BigNumber f is created with value 30.
BigNumber g = "2060"; //BigNumber g is created with value 2060.
BigNumber h(22); //BigNumber h is created with value 22.
## Methods
### `add(BigNumber other)`
Adds another BigNumber to the current instance
`BigNumber("4").add(BigNumber("20")) => BigNumber("24")`
### `subtract(BigNumber other)`
Subtracts another BigNumber from the current instance
`BigNumber("30").subtract(BigNumber("45")) => BigNumber("-15")`
### `multiply(BigNumber other)`
Multiplies the BigNumber by another BigNumber
`BigNumber("12").multiply(BigNumber("4")) => BigNumber("48")`
### `divide(BigNumber other)`
Divides the BigNumber by another BigNumber
`BigNumber("30").divide(BigNumber("5")) => BigNumber("6")`
### `pow(int exponent)`
Raises the BigNumber to the power of the exponent
`BigNumber("2").pow(3) => BigNumber("8")`
### `getString()`
Returns the BigNumber as an std::string
`BigNumber("3824").getString() => "3824"`
### `setString(std::string newStr)`
Sets the BigNumber's internal number string to a new string
`BigNumber("2847").setString("38") => BigNumber("38")`
### `negate()`
Changes the sign of the BigNumber
BigNumber("3").negate() => BigNumber("-3")
BigNumber("-27").negate() => BigNumber("27")
### `equals(BigNumber other)`
Checks if the other BigNumber is equal to this one
`BigNumber("24").equals(BigNumber("28")) => false`
### `digits()`
Returns the number of digits in the BigNumber
`BigNumber("28374").digits() => 5`
### `isNegative()`
Determines whether a BigNumber is negative
`BigNumber("-278").isNegative() => true`
### `isPositive()`
Determines whether a BigNumber is positive
`BigNumber("-3").isPositive() => false`
### `isEven()`
Determines whether a BigNumber is even
`BigNumber("28472310").isEven() => true`
### `isOdd()`
Determines whether a BigNumber is odd
`BigNumber("283427").isOdd() => true`
### `abs()`
Gets the absolute value of the BigNumber
`BigNumber("-26").abs() => BigNumber("26")`
## Operator overloads
The following operators have been overloaded to work with BigNumbers:
### `<<`
Output stream operator
`std::cout << BigNumber("26") << std::endl => 26`
### `+`
Addition operator
`BigNumber("2") + BigNumber("4") => BigNumber("6")`
### `-`
Subtraction operator
`BigNumber("0") - BigNumber("2000") => BigNumber("-2000")`
### `*`
Multiplication operator
`BigNumber("-20") * BigNumber("-5") => BigNumber("100")`
### `/`
Division operator
`BigNumber("10") / BigNumber("-2") => BigNumber("-5")`
### `==`
Equal to operator
`BigNumber("24") == BigNumber("24") => true`
### `>`
Greater than operator
`BigNumber("2") > BigNumber("6") => false`
### `<`
Less than operator
`BigNumber("2") < BigNumber("6") => true`
### `>=`
Greater than or equal to operator
`BigNumber("34") >= BigNumber("22") => true`
### `<=`
Less than or equal to operator
`BigNumber("383") <= BigNumber("383") => true`
### `=`
Assignment operator
`BigNumber c("3") = BigNumber("8") => BigNumber("8")`
### `+=`
Adds and assigns to the BigNumber
`BigNumber c("4") += BigNumber("3") => BigNumber("7")`
### `-=`
Subtracts and assigns to the BigNumber
`BigNumber c("28") -= BigNumber("3") => BigNumber("25")`
### `*=`
Multiplies and assigns to the BigNumber
`BigNumber c("3") *= BigNumber("4") => BigNumber("12")`
### `/=`
Divides and assigns to the BigNumber
`BigNumber c("30") /= BigNumber("30") => BigNumer("1")`
### `++ (Prefix)`
Increments the BigNumber and returns the newly incremented number
`++BigNumber("10") => BigNumber("11")`
### `-- (Prefix)`
Decrements the BigNumber and returns the newly decremented number
`--BigNumber("34") => BigNumber("33")`
### `++ (Postfix)`
Increments the BigNumber but returns the original value
`BigNumber("20")++ => BigNumber("20")`
### `-- (Postfix)`
Decrements the BigNumber but returns the original value
`BigNumber("14")-- => BigNumber("14")`
### `[]`
Indexing operator
`BigNumber d("26")[1] => 6`
## License
This project is under the [Apache License](https://github.com/Limeoats/BigNumber/blob/master/LICENSE.md).
## Credit
The BigNumber class was created by [Mark Guerra](http://www.twitter.com/Limeoats). Visit
[Limeoats.com](http://www.limeoats.com) for more information.