while-loop

问题 As title says, I don't understand why f^:proposition^:_ y is a while loop. I have actually used it a couple times, but I don't understand how it works. I get that ^: repeats functions, but I'm confused by its double use in that statement. I also can't understand why f^:proposition^:a: y works. This is the same as the previous one but returns the values from all the iterations, instead of only the last one as did the one above. a: is an empty box and I get that has a special meaning used with

问题 As title says, I don't understand why f^:proposition^:_ y is a while loop. I have actually used it a couple times, but I don't understand how it works. I get that ^: repeats functions, but I'm confused by its double use in that statement. I also can't understand why f^:proposition^:a: y works. This is the same as the previous one but returns the values from all the iterations, instead of only the last one as did the one above. a: is an empty box and I get that has a special meaning used with

问题 I'm trying to create a script that will read text files and then analyse them, regardless of whether the text file is online or offline. The offline part is done, using open(FILENAME, "anyfilename.txt") analyze_file(); sub analyze_file { while (<FILENAME>) {analyze analyze} } Now for the online part, is there anyway to read a text file on a website and then "open" it? What I hope to achieve is this: if ($offline) { open(FILENAME, "anyfilename.txt") } elsif ($online) { ##somehow open the http

问题 This question already has an answer here : Loop doesn't see value changed by other thread without a print statement (1 answer) Closed 4 years ago . I have a while loop running in my Java program's main method. The loop is supposed to run until a boolean flag variable is set to true in the program's keyPressed method (I added the program as a KeyListener to a JFrame). import java.awt.event.KeyEvent; import java.awt.event.KeyListener; import javax.swing.JFrame; public class ThreadWhile

问题 When looking through some code that was handled by another employee, I see a lot of code written in: do{ ... }while(false); What advantage (if any) does this provide? Here is more of a skeleton that is happening in the code: try{ do{ // Set some variables for(...) { if(...) break; // Do some more stuff if(...) break; // Do some more stuff } }while(false); }catch(Exception e) { // Exception handling } Update: C++ Version: Are do-while-false loops common? 回答1: Maybe it was done to be able to

问题 I have a section of code where I check the input to scanf is valid. i.e. if scanf returns a non zero positive number. This is part of my code: while(scanf(" %d",&choice)<=0){ printf("Incorrect value entered, please re-enter\n"); } Where “choice” is an integer. Every time I run this code, the compiler skips past the scanf after the while loops is executed. I get an output like this: Welcome to the Predator/Prey Calculator Please enter your name Dan Hi Dan Please choose one of the following

问题 Sorry I am a noob I've read countless tutorials about making a simple timer and was wondering why it doesn't work until I noticed it is the while-loop causing the issue o.O I have removed it and then it works but only 1 time I need to use the loop though so the movement finishes :C Heres the code: old_x is the coordinate from an ImageView and new_x from the onTouch Event, maybe the problem because I am casting them as an int? I don't know what I need to do so it works please help O: while(old

问题 So basically I want to copy everything i write to stdin (including newline char) to string for hash purposes. I managed to accomplish that and made small code to represent my problem. #include <stdio.h> #include <string.h> #include <stdlib.h> #define BUFFERSIZE 10000 int main() { char *myStr = calloc(1,1); char buffer[BUFFERSIZE]; while( fgets(buffer, BUFFERSIZE , stdin) != NULL ){ myStr = realloc(myStr, strlen(myStr)+1+strlen(buffer) ); strcat( myStr, buffer ); } printf("\n%s\n",myStr); }

问题 When I'm compiling this code public static void main(String [] args) { int x = 0; while(false) { System.out.println(hello); } } it is showing compile time error unreachable code. But when I modified this code to public static void main(String [] args) { int x = 0; boolean result = false; while(result) { x=4; } } it's working fine. Can somebody tell me the reason behind this behavior. 回答1: It is because boolean result = false is not a constant expression whereas false is. If you try the code

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 4 years ago . I use while true loop in many projects. It serves me well and it's not over-complicated. So, why it is a bad idea to use while true loop infinitely running background processes. Thanks for your answers. 回答1: My project leader doesn't allow this kind of loop in my code, he's