bigint

1.拉链（zip） 将两个集合进行 对偶元组合并，可以使用拉链 object Demo_031 { def main(args: Array[String]): Unit = { val list1 = List(1, 2 ,3) val list2 = List(4, 5, 6) val list3 = list1.zip(list2) // (1,4),(2,5),(3,6) println("list3=" + list3) } } 　　输出 注意事项 拉链的本质就是两个集合的合并操作，合并后每个元素是一个对偶元组。 操作的规则下图: 如果两个集合个数不对应，会造成数据丢失。 集合不限于List, 也可以是其它集合比如 Array 如果要取出合并后的各个对偶元组的数据，可以遍历 for(item<-list3){ print(item._1 + " " + item._2) //取出时，按照元组的方式取出即可 } 　　 2.迭代器（Iterator） 通过iterator方法从集合获得一个迭代器，通过while循环和for表达式对集合进行遍历 实例： object Demo_032 { def main(args: Array[String]): Unit = { val iterator = List(1, 2, 3, 4, 5).iterator // 得到迭代器

I've got four unsigned 32-bit integers representing an unsigned 128-bit integer, in little endian order: typedef struct { unsigned int part[4]; } bigint_t; I'd like to convert this number into its decimal string representation and output it to a file. Right now, I'm using a bigint_divmod10 function to divide the number by 10, keeping track of the remainder. I call this function repeatedly, outputting the remainder as a digit, until the number is zero. It's pretty slow. Is this the fastest way to do it? If so, is there a clever way to implement this function that I'm not seeing? I've tried

直接扣js代码 　　 $w = {}; if (typeof $w.RSAUtils === 'undefined') var RSAUtils = $w.RSAUtils = {}; var biRadixBase = 2; var biRadixBits = 16; var bitsPerDigit = biRadixBits; var biRadix = 1 << 16; var biHalfRadix = biRadix >>> 1; var biRadixSquared = biRadix * biRadix; var maxDigitVal = biRadix - 1; var maxInteger = 9999999999999998; var maxDigits; var ZERO_ARRAY; var bigZero, bigOne; var BigInt = $w.BigInt = function(flag) { if (typeof flag == "boolean" && flag == true) { this.digits = null; } else { this.digits = ZERO_ARRAY.slice(0); } this.isNeg = false; }; RSAUtils.setMaxDigits = function(value)

How do arbitrary-precision libraries like GMP store extremely large floating-point numbers represented in memory? I would imagine that if for instance you wanted to compute Pi or Euler's constant to say, 2,000,000 digits that you would allocate a massive array of bytes for the digits to the right of the decimal place. Each byte would store 2 decimal place values and the array would be a member of a data structure with the number of digits and number of bytes used to store the value. Is this how it works? Current computers have 32 or 64-bit registers, so doing calculations on bytes is very

This question already has an answer here: Is it possible to use SSE and SSE2 to make a 128-bit wide integer? 1 answer My impression is definitely not but perhaps there is a clever trick? Thanks. Not directly, but there are 64 bit arithmetic operations which can be easily combined to perform 128 bit (or greater) precision. The xmm registers can do arithmetics on 8, 16, 32 and 64 bit integers. It doesn't produce a carry flag so you can't extend the precision beyond 64 bits. The extended precision math libraries use the general purpose registers which are 32 bit or 64 bit, depending on the OS. 来源

I would like to create a bigint (or string or whatever that is not int ) typed primary key field under Rails 3. I have a given structure of data, for example: things ------ id bigint primary_key name char(32) The approach I'm currently trying to push: create_table :things, :id => false do |t| # That prevents the creation of (id int) PK t.integer :id, :limit => 8 # That makes the column type bigint t.string :name, :limit => 32 t.primary_key :id # This is perfectly ignored :-( end The column type will be correct, but the primary key option will not be present with sqlite3 and I suspect that this

Seems like BIGINT is the biggest integer available on MySQL, right? What to do when you need to store a BIGINT(80) for example? Why in some cases, like somewhere in the Twitter API docs, they recommend us to store these large integers as varchar ? Which is the real reason behind the choice of using one type over another? Big integers aren't actually limited to 20 digits, they're limited to the numbers that can be expressed in 64 bits (for example, the number 99,999,999,999,999,999,999 is not a valid big integer despite it being 20 digits long). The reason you have this limitation is that

I was wondering if any fellow SO's could recommend a good light-weight fixed size integer type (128-bit or even 256-bit, possibly even template parametrized) library. I've had a look at GMP and co, they care great, yet are a bit too large for my purposes, I'm interested in simple header only solutions at this point. Performance is important and the target architecture will be x86 and x86-64, also a reasonable license (aka nothing GPL or LGPL). The Boost library has data types as part of multiprecision library, for types ranging from 128 to 1024 bits. #include <boost/multiprecision/cpp_int.hpp>

According to the MySQL website, the signed bigint can go up to 18446744073709551615. What if I need a number bigger than that for the auto-incrementing primary key? 9000 If you insert 1 million records per second 24x7, it will take 584542 years to reach the limit. I hope by then a next version of MySQL will support bigger ID columns, and developers will all be able to do back-of-the-envelope calculations before posting to Stack Overflow :) Sourav With such a number (1 to 18446744073709551615), you can give all the animals on the earth a unique ID :) Ben I suppose you're screwed? You could get

Trying to create a table with a bigint column creates a standard integer column instead. What could be going wrong? I don't know where to start looking. I'm using this in the migration: create_table :table_name do |t| t.integer :really_big_int, limit: 8 end I'm using Ruby 1.9.2, PostgreSQL 9.0.3 and Rails 3.0.9. I've dropped the database and ran the migrations several times and it still doesn't create the bigint column. Chris Barretto For some reason the create table doesn't like bigint. You can, however do it with add_columm using the bigint data type: add_column :table_name, :really_big_int,