A very Easy to use Big Integer (EBI) C++ library

The EBI (Easy to use Big Integer) is a multiple precision integer C++ library. The main feature is extremely easy to use. Source code is fairly simple. Basic C/C++ programming knowledge is enough to use and understand the implementation.

Demo

C++ Code:

	ebi a = "12345678901234567890123456789";
	cout << "Big number a = \"" << a << "\"" << endl;
	ebi b;
	cout << "Please keyin a big number, e.g. 9876543210 or 0x24cb016ea:" << endl;
	cin >> b;
	cout << "Your number, b, is " << dec << b << " (0x" << hex << b << ")" << endl;
	cout << endl;
	cout << "a+b = " << dec << a+b << endl;
	cout << "a-b = " << dec << a-b << endl;
	cout << "a*b = " << dec << a*b << endl;
	cout << "a/b = " << dec << a/b << endl;
	cout << "a\%b = " << dec << a%b << endl;

Output:

	Big number a = "12345678901234567890123456789"
	Please keyin a big number, e.g. 9876543210 or 0x24cb016ea:
	0x24cb016ea
	Your number, b, is 9876543210 (0x24cb016ea)

	a+b = 12345678901234567899999999999
	a-b = 12345678901234567880246913579
	a*b = 121932631124828532112482853211126352690
	a/b = 1249999988734374999
	a%b = 156249999

Features

• Source code is fairly simply, easy to use and understand
• Both decimal and hexadecimal formats are supported
• Small memory footprint

Build

To try out the ebi C++ library, you only need to download three files, i.e. ebi.h, ebi.cpp and demo0.cpp.

Under a Linux environment:

	$ gcc -std=c++11 -o demo demo0.cpp ebi.cpp
	$ ./demo

Under a Windows environment with CodeBlocks 17.12:

	Settings -> Compiler...
		Select "Compiler settings"
		Select "Compiler Flags"
		Select "Have g++ follow the C++11 ISO C++ language standard [-std=c++11]"
		Press OK buttom
	Build -> Build and run (F9)

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Implementation details

• The c++11 features are used in the ebi library which has been supported by most of widely used compilers (C++ compiler support)
• Little-endian is implemented, i.e. highest address as the Most Significant Byte (MSB)
• The backbone data structure is a uint8_t array (or unsigned char array); thus, the ebi library has following advantages:
  • The ebi library is efficient in terms of memory usage
  • Shift operators have the same physical memory meaning as int type

Implementation guidelines

• Other than constructors and internal functons (base_*), all of array pointers, uint8_t *data, are pointing allocated and independent memory location.
• The internal array structure is unsigned (thus, without sign-extension).

Development platform

• CentOS Linux 7
• x86-64 ISA
• gcc (GCC) 4.8.5

Issue-raising is welcomed

The first motivation of ebi C++ library is simple, easy to use and understand. And, yea, issue raising is welcomed. ^^