numbers | 易学教程

How do I find the difference between two values without knowing which is larger?

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问题 I was wondering if there was a function built into Python that can determine the distance between two rational numbers but without me telling it which number is larger. e.g. >>>distance(6,3) 3 >>>distance(3,6) 3 Obviously I could write a simple definition to calculate which is larger and then just do a simple subtraction: def distance(x, y): if x >= y: result = x - y else: result = y - x return result but I'd rather not have to call a custom function like this. From my limited experience I've

Why does bitwise “not 1” equal -2?

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Suppose we have 1 and this number in base 2 is: 00000000000000000000000000000001 Now I want to flip all bits to get following result: 11111111111111111111111111111110 As far as I know, the solution is to use the ~ (bitwise NOT operator) to flip all bits, but the result of ~1 is -2 : console.log(~1); //-2 console.log((~1).toString(2)); //-10 (binary representation) Why do I get this strange result? Cerbrus There are 2 integers between 1 and -2 : 0 and -1 1 in binary is 00000000000000000000000000000001 0 in binary is 00000000000000000000000000000000 -1 in binary is

Mysql search for string and number using MATCH() AGAINST()

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I have a problem with the MATCH AGAINST function. The following query give me the same result: SELECT * FROM models MATCH(name) AGAINST('Fiat 500') SELECT * FROM models MATCH(name) AGAINST('Fiat') How can I search for both strings and numbers in a column of a FULL TEXT table? Thanks If you need Fiat and 500 anywhere where order does not matter, then SELECT * FROM models MATCH(name) AGAINST('+Fiat +500'); If you need Fiat 500 together, then SELECT * FROM models MATCH(name) AGAINST('+"Fiat 500"'); If you need Fiat and zero or more 500 , then SELECT * FROM models MATCH(name) AGAINST('+Fiat 500');

how to avoid number repeation by using random class in c#?

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问题 hi i am using Random class for getting random numbers but my requirement is once it generate one no that should not be repeate again pls help me. 回答1: Keep a list of the generated numbers and check this list before returning the next random. Since you have not specified a language, I'll use C# List<int> generated = new List<int>; public int Next() { int r; do { r = Random.Next() } while generated.Contains(r); generated.Add(r); return r; } 回答2: The following C# code shows how to obtain 7

Is there a Java library for unsigned number type wrappers? [closed]

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Obviously, Java doesn't support unsigned number types natively, and that's not going to change soon (comments starting in 2002). However, when working with databases, such as MySQL, they may come in handy every now and then. There are a lot of questions dealing with how to simulate unsigned numbers. For example: unsigned short in java Java: Unsigned numbers Understanding Java unsigned numbers All of them superficially describe how it could be done. But is there any library actually going all the way and implementing suitable wrappers for UByte , UShort , UInteger , ULong ? Preferably, those

MySQL UPDATE with random number between 1-3

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Got a big table and I want to add a column that has a randomly chosen number for each record. 1, 2, or 3. Having a hard time. Any ideas? Rabbie Try this: UPDATE tableName SET columnName = FLOOR( 1 + RAND( ) *3 ); From the MySQL documentation for RAND : Returns a random floating-point value v in the range 0 <= v < 1.0. So in the above query, the largest value which could be generated by 1 + RAND()*3 would be 3.999999 , which when floored would give 3. The smallest value would occur when RAND() returns 0, in which case this would give 1. Faisal Use RAND() function. It returns a random floating

How to prevent inserting value that is greater than to max in number field in html

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问题 I am using number field in html5, here is my code, <input type="number" class="edit-items" /> i set the max of this number field using javascript. element.max = quantity; element.min = 0; element.step = 1; If i am using the arrow-up in the number field. Greater value than the max is not possible. But when I tried to insert in the field, greater value than the max is possible. I would like to prevent it. How? 回答1: Like you said input of type number will work fine with arrows and not with

Java如何声明一个数组？JS如何声明一个数组？如何获取数组长度

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1 Long[] numbers; //一般使用的定义方式，可分为静态和动态两种定义方式，下有说明. 2 Long numbers[]; //跟上面用法一致. 3 Long... numbers; //只能用于函数中形参的定义. 4 []Long numbers; //错误的定义方式，没这种写法. 5 6 静态定义： 7 int[] numbers = {1, 2, 3, 4, 5}; 8 动态定义： 9 int size = 5; 10 int[] numbers = new int[size]; 11 for (int i = 0; i < size; i++) { 12 numbers[i] = i + 1; 13 } 14 15 int... xx 的形参定义： 16 public void testArray(int... numbers) { 17 for (int i : numbers) { 18 //打印传过来的形式参数的所有元素. 19 System.out.println(i); 20 } 21 } js声明一个空数组 var myArray = []; var myArray1 = new Array(); var myArray2 = new Array(3); 1 public class Test { 2 public static void main

Limits of Nat type in Shapeless

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In shapeless, the Nat type represents a way to encode natural numbers at a type level. This is used for example for fixed size lists. You can even do calculations on type level, e.g. append a list of N elements to a list of K elements and get back a list that is known at compile time to have N+K elements. Is this representation capable of representing large numbers, e.g. 1000000 or 2 53 , or will this cause the Scala compiler to give up? I will attempt one myself. I will gladly accept a better answer from Travis Brown or Miles Sabin. Nat can currently not be used to represent large numbers In

What is 0x10 in decimal?

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I have the following code: SN.get_Chars(5) SN is a string so this should give the 5th Char. Ok! Now I have another code but: SN.get_Chars(0x10) I wonder what 0x10 is? Is it a number? If it's so, then what is it in decimal notation? 0x means the number is hexadecimal , or base 16. 0x10 is 16. paxdiablo 0xNNNN (not necessarily four digits) represents, in C at least, a hexadecimal (base-16 because 'hex' is 6 and 'dec' is 10 in Latin-derived languages) number, where N is one of the digits 0 through 9 or A through F (or their lower case equivalents, either representing 10 through 15), and there may