addition | 易学教程

What is the cost of + operation on a String in Java?

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问题 For this for loop, is the run time O(n) or O(n^2): char[] ar = new char[1000]; String s = ""; Arrays.fill(ar, 'a'); for(Character c: ar){ s += c; } So basically, what is the run time of + on a String? How does it work behind the scene in Java? 回答1: Java strings are immutable. Every time you do: s+=c; You're really saying: s = new String(s + c); new String(s + c) must allocate a string of length s + 1, or: 1 2 3 4 5 6 7 8 9 ... etc. Since Sum(1..N) == (n + 1) (n / 2), this is O(n^2). One of

Im looking for a way to add up elements of two arrays

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问题 i am looking for a way that i can add up elements in an array such that the first element of the first array is added to every element in the second array, then the second element in the first array is added to all every element in the second array and so on. The final vector will be length(a)*length(b) long for example... a=[1,2,3,4] b=[5,6,7] answer = [(1+5),(1+6),(1+7),(2+5),(2+6),(2+7),(3+5),(3+6),(3+7),(4+5),(4+6),(4+7)] =[6,7,8,7,8,9,8,9,10,9,10,11] 回答1: My first thought is to do this

C - Exception when using _int16 [duplicate]

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问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Correct way to use scanf / printf (and family) with fixed size types? I have written the following program in Visual Studio: Upon running the program and exiting, I get the error message "stack around variable b was corrupted". If I replace _int 16 with int, no exception is raised. How can I solve this problem please? I have to use _int16 since I want to simulate an integer overflow. Thanks :) 回答1: As pointed

Basic Javascript math text field

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问题 hello im new and learning javascript. I'm trying to make a program of addition through text field. Check the html code on js fiddle http://jsfiddle.net/fCXMt/ What I need to know is how can I accept user input in text field and diplay output in P tag. <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>untitled</title> </head> <body> <input id="value1" type="text" /> <span> + </span> <input id="value2" type="text" /> <input type="submit" onclick="output();"> <p id="result">

Java Integer addition [closed]

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问题 This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center. Closed 7 years ago . my program has the user enter some 5 digit number, I need a way to take that 5 digit integer and add all the digits together. For example, the user

Add numbers with the word “add”

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问题 I am writing to offer an application in Java right now and instead of using the operator "+", the user of the application can literally use the word "add" to add two numbers together. I'm quite stuck on how to do this because I can't really use a method in order to complete the function considering I'd have to type "add()" rather than just "add". Unless there is a way to execute a method without the parentheses. Would I have to write a completely new class or is there an easier way to do this

SQL Adding integer strings with zero values

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问题 I am trying to add strings which are integers. I have 201404 as input and I need it to be converted to 201503 so the only way to do this is to increase the year (2014) by 1 and decrease the month 02 by 1. I have tried the below but the leading zero in the month does not seem to preserve: DECLARE @YearMonth INT = 201404 , @left INT = 0 , @right INT = 0 SET @YearMonth = CAST(@YearMonth AS VARCHAR(6)) SET @left = CAST(LEFT(@YearMonth, 4) + 1 AS VARCHAR(MAX)) SET @right = RIGHT(@YearMonth, 2) - 1

C# - Find/Edit/Replace String

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问题 I am trying to retrieve data from a file to change it and replace the old data. I have a file that looks something like this: TEXT NEXT_TEXT 10.505 -174.994 0 TEXT NEXT_TEXT 100.005 174.994 90 TEXT NEXT_TEXT -10.000 -5.555 180 TEXT NEXT_TEXT -500.987 5.123 270 TEXT NEXT_TEXT 987.123 1.000 180 TEXT NEXT_TEXT 234.567 200.999 90 I am trying to grab the 3rd and 4th columns to change the data based on what a user inputs into two TextBoxes . Let's label the 3rd column "X" and the 4th column "Y" .

how to set auxiliary flag for 16bits binary addition

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问题 I know that when performing an 8-bit binary addition, the auxiliary flag is set to 1 if there is a carry from 3rd bit to 4th bit; but what about the addition of 2 16-bit numbers? i can't see any clear answer on the web. I'm studying intel 8086 microprocessor... For example, when i add these 2 numbers, 0x30a2 and 0xf1ac 0011 0000 1010 0010 + 1111 0001 1010 1100 CF=1 ZF=0 PF=1 SF=0 OF=1 AF=? I'm not sure where to check it 回答1: From "Programming the 8086/8088" by James W. Coffron: AF auxiliary

Adding multiple values in one column comma separated

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问题 If I have a CLOB field that contains multiple values separated by commas, and need to total them to get a final output, how can I achieve that in SQL Developer? Example table: STOCK | COST ABCDE | 258.40,299.50 FGHIJ | 100.50,70.50,95.30 I would like to be able to select the total for each row. For ABCDE looking to select a total of 557.90 For FGHIJ looking to select a total of 266.30 回答1: If you have Oracle 12, you can use LATERAL: select t.stock, sum(to_number(p.cst,'9999999.9999')) total