How do you input a string via Serial Terminal and do BigNumber calculations

I was wondering how you input a series of numbers via the serial terminal and do big number calculations.
Also, how can you create a variable that you can do big number calculations.

RIght now I have been doing the big number calculations by setting constants:

BigNumber FRAC1 = "11359573";
BigNumber FRAC2 = "512";
BigNumber MOD2 = "1536";

is there anything to go string.bigNumber etc.

see my code below for terminal input.


#include <SPI.h>
#include <BigNumber.h>
  String str, str1, str2;

void setup() {
  Serial.begin (9600);
  Serial.println ();
  Serial.println ();


  BigNumber::begin (40);  // initialize library
  BigNumber::setScale (15);

void loop () {

  //BigNumber N30;
   Serial.println("Enter a value for 'FRAC1', Press ENTER");
   while (Serial.available() == 0) ;  // Wait here until input buffer has a character
   {  str = Serial.readStringUntil('\n');
   Serial.println("Enter a value for 'FRAC2', Press ENTER");
   while (Serial.available() == 0) ;
     str1 = Serial.readStringUntil('\n');

   Serial.println("Enter a value for 'MOD2', Press ENTER");
   while (Serial.available() == 0) ;
     str2 = Serial.readStringUntil('\n');

   BigNumber N30 = str1/str2;


Looking at the BigNumber library, you can construct a BigNumber object using a C-style character string (not String with capital S).

From the library:

BigNumber::BigNumber (const char * s)

Something in the line of

char txtbuffer[64];
str1.toCharArray(txtbuffer, str1.length());

BigNum bn1 = new BigNum(txtbuffer);



Not tested (I don't use String with capital S and I am not much of a C++ programmer).

Thanks. I tried that and I got the following error:

Arduino: 1.6.7 (Windows 7), Board: "Arduino Due (Programming Port)"

C:\Users\Mark\Documents\Arduino\ADF5355_3\ADF5355_3.ino: In function 'void loop()':

ADF5355_3:198: error: invalid conversion from 'BigNumber*' to 'int' [-fpermissive]

BigNumber bn1 = new BigNumber(txtbuffer);


In file included from C:\Users\Mark\Documents\Arduino\ADF5355_3\ADF5355_3.ino:6:0:

C:\Users\Mark\Documents\Arduino\libraries\BigNumber/BigNumber.h:36:3: error: initializing argument 1 of 'BigNumber::BigNumber(int)' [-fpermissive]

BigNumber (const int n); // constructor from int


exit status 1
invalid conversion from 'BigNumber*' to 'int' [-fpermissive]

This report would have more information with
"Show verbose output during compilation"
enabled in File > Preferences.

In which case I have no idea as I'm not much of a C++ programmer. Sorry.