for-loop

问题 I'm a student trying to figure out how to fix a seemingly simple problem. I keep getting an error while trying to initialize 2 variables in a FOR loop. I'm trying to create rows for a game board. Why am I getting this error? This is the method: public String [] board; public void printBoard(){ for(int i, j = 0; i < this.board.length; i++, j++) if(j > 10) System.out.println(); else System.out.print(this.board[i]); > java:39: error: variable i might not have been initialized 回答1: It's because

问题 I see these used interchangeably. What's the difference? 回答1: There is no difference. From perldoc perlsyn: The foreach keyword is actually a synonym for the for keyword, so you can use foreach for readability or for for brevity. 回答2: I see these used interchangeably. There is no difference other than that of syntax. 回答3: Four letters. They're functionally identical, just spelled differently. 回答4: Ever since its introduction in perl-2.0, foreach has been synonymous with for . It's a nod to

问题 This question already has answers here : The literal xyz of type int is out of range (5 answers) Closed 5 years ago . I was trying to do some Project Euler question which involves pandigital numbers with special divisibility requirements of the first 5 prime numbers, and thought that this would be the starting point (see, 1023456789 is the first number being looked at, and 9876543210 is the last one). import java.util.*; public class pandigital_special { public static void main (String args[]

问题 I tried this for almost two days but still nothing. Maybe someone can help who is highly skilled in javascript loops. I have this code: $(function(){ var len = $('#groupContainer > div').length; var arr = []; for(var i=0; i < len; i++){ var number = $('#number_' + [i + 1]); var date = $('#date_' + [i + 1]); var count = i + 1; var message =""; console.log(number) var a = number.map(function(){ return this.value; }); var b = date.map(function(){ return this.value; }); var newObj = {number: a[0]

问题 In the past I have written R code that requires for loops inside of for loops. Generally this code is rather time consuming to execute. I have read online this is a result of how for loops in R work. I have also read that using for loops in another language inside R e.g. C++ or Java, can speed up the computational time. Does anyone have experience with this and can point me to some simple examples that I can read? Also can you call another language for the for loop, but still have everything

问题 I have the following code, which plots 4 lines: plot for [i=1:4] \ path_to_file using 1:(column(i)) , \ I also want to plot 8 horizontal lines on this graph, the values of which come from mydata.txt. I have seen, from the answer to Gnuplot: How to load and display single numeric value from data file, that I can use the stats command to access the constant values I am interested in. I think I can access the cell (row, col) as follows: stats 'mydata.txt' every ::row::row using col nooutput

问题 I have installed PHP using wamp server in Windows and I have give the entry for Xdebug in php.ini And Debugging not working in netbeans. How to solve this? Thanks 回答1: If you are using wamp server in windows, make sure you edit the correct php.ini file (open php.ini FROM WAMP TRAY MENU) or check the path to your used php.ini file in phpinfo(). The path to your dll file looks like it might be wrong. Under WAMP it would normally point to something like zend_extension_ts="C:\wamp\bin\php\php5.2

问题 I have probably a stupid question, but I just can not understand the logic behind it. Question 1: a = c(10,20,30) b = c(15,30,45) c = cbind(a,b) for ( i in 1:ncol(c)) {d[i] = c[i]+2} print(d) # Error d not defined Then I thought maybe I need a placeholder for the question, so I did the followings: Question 2: d = matrix(NA, 3,2) # now have the same dimension as c for ( i in 1:ncol(c)){d[i] = c[i]+2} the output is [,1] [,2] [1,] 12 NA [2,] 22 NA [3,] NA NA I cannot interpret the above output.

问题 I have a large dataset for which I want to get the value of each row minus the following row except for each fifth row. With a for loop, it is fairly simple but with my large dataset, it takes over an hour. I've been told that apply with a function is MUCH faster, but I don't know how to write a complicated function and I can't find examples of similar problems. #set up matrix x=matrix(0,15,2) x[,1]=c(1, 5, 4, 3, 4, 2, 4, 3, 7, 8, 3, 2, 9, 7, 3) #run for loop for (i in c(0:((nrow(x)/5)-1)*5))

问题 I have created a function which applies a Cox regression model to test data, creates survival functions based on covariates, and then predicts the survival probability 30 days from current time for each test observation. The example below uses the lung dataset and works quite well. However, applied to my own data the processing time is tedious. For n = 60000, I just stopped it after an hour as it is not practical for what I intend to use the program for. Looking at the code structure, is