while-loop

问题 I am trying to write a program that reads numbers input by the user until the user types done. If the user types a non-number other than "done," I want to return an error message like "please enter a number number. When the user types "done", I want to calculate the total of the numbers, the number count and the average. I have tried to create a while loop with try and except to catch the non-numeric error other than done. That is part of the trick, a string entry is an error unless the

问题 Being very new to Haskell, I'm wondering how to 1) compute something until a certain criterion is satisfied, and then 2) return the computed value. In the languages I know, you would use a while loop for that. How do you do it in Haskell? 回答1: You should use recursion : func :: <function type> func <arguments> = if condition then <recursive call> else computedValue There are also other utilities you'll discover in the future, such as until, that will help you with this. In the end it really

问题 Being very new to Haskell, I'm wondering how to 1) compute something until a certain criterion is satisfied, and then 2) return the computed value. In the languages I know, you would use a while loop for that. How do you do it in Haskell? 回答1: You should use recursion : func :: <function type> func <arguments> = if condition then <recursive call> else computedValue There are also other utilities you'll discover in the future, such as until, that will help you with this. In the end it really

问题 Being very new to Haskell, I'm wondering how to 1) compute something until a certain criterion is satisfied, and then 2) return the computed value. In the languages I know, you would use a while loop for that. How do you do it in Haskell? 回答1: You should use recursion : func :: <function type> func <arguments> = if condition then <recursive call> else computedValue There are also other utilities you'll discover in the future, such as until, that will help you with this. In the end it really

问题 This question already has answers here : scanf() leaves the new line char in the buffer (4 answers) How to read / parse input in C? The FAQ (1 answer) Closed 2 years ago . I want to implement a simple code to print the error message when the type of input is not an integer. Below is a sample code. int num; while (1) { printf("Input the value of integer: "); int result = scanf(" %d", &num); if (result == 0) { printf("ERROR-Not an integer.\n"); } else if (num < 0) { printf("ERROR- Not positive.

问题 I am making an automation program using Watir , that reads links from a file links.txt and then open one by one on chrome browser. When it takes to much time to open then browser and its on loading time it shows me the Net::ReadTimeout . I have tried to rescue and and if its not rescued go to the next link from the list. I have tried this one but when max_retries = 3 it shows again the error. I want to make browser to wait for specific amount of time and then if it is still loading close the

问题 I read the following code in "Thinking in java". synchronized(obj) { while (condition_not_matched) { obj.wait(); } //continue dosomething(); } What I think: Use "if" is OK, because the "wait" means it must get the obj's lock monitor, and only one thread can executed here. (1)Why here use "while (condition)" not "if" ? (2)What happend when executed "obj.wait()"? Does the currrent thread release the lock of "obj"? (3)And when another thread executed "obj.notify()", what happend of the previous

问题 I read the following code in "Thinking in java". synchronized(obj) { while (condition_not_matched) { obj.wait(); } //continue dosomething(); } What I think: Use "if" is OK, because the "wait" means it must get the obj's lock monitor, and only one thread can executed here. (1)Why here use "while (condition)" not "if" ? (2)What happend when executed "obj.wait()"? Does the currrent thread release the lock of "obj"? (3)And when another thread executed "obj.notify()", what happend of the previous

问题 I read the following code in "Thinking in java". synchronized(obj) { while (condition_not_matched) { obj.wait(); } //continue dosomething(); } What I think: Use "if" is OK, because the "wait" means it must get the obj's lock monitor, and only one thread can executed here. (1)Why here use "while (condition)" not "if" ? (2)What happend when executed "obj.wait()"? Does the currrent thread release the lock of "obj"? (3)And when another thread executed "obj.notify()", what happend of the previous

问题 Im trying to do an infinite loop using while between 0 to 100 and 100 to 0, but the browser crashes. There is a way to clear the browser memory? This is my code: var a = 0; var flag = true; while (true) { if (a < 100 && flag == true) { a++; } else { a = 0; flag = false; if (a < 0) { flag = true; } } console.log(a); } 回答1: An infinite while loop will block the main thread wich is equivalent to a crash. You could use a selfcalling function ( wich leaves the main thread doing some other stuff