created: 02/20/2018

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CHAPTER 56 — Big Integer

Sometimes you need to compute with very large numbers. The primitive type int is only 32 bits, which limits the size of integers to plus-or-minus 231, roughly plus-or-minus two billion. The primitive type long is 64 bits, but sometimes even this is too limited. Especially in cryptography and other number theory applications you need integers of unlimited size.

This chapter discusses the class BigInteger which implements arbitrary-precision integers. This means integers, both positive and negative, can be of any magnitude.

BigIntegers are not required for the AP Java test.

Chapter Topics:


(Trick Question: ) What is the output of the following fragment?

if ( 1_000_000_000 + 2_000_000_000 > 0 )
    System.out.println("Obviously True");

Note: the literals in the if statement are correct. In Java version 7 and later, underscores can be used inside numeric literals to make reading easier. Don't put them at the start or end of a literal, though.

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