I am trying to plot some data from a camera in real time using OpenCV. However, the real-time plotting (using matplotlib) doesn’t seem to be working. I’ve isolated the problem into this simple example: fig = plt.figure() plt.axis([0, 1000, 0, 1]) i = 0 x = list() y = list() while i < 1000: temp_y … Read more
I’ve noticed the following code is legal in Python. My question is why? Is there a specific reason? n = 5 while n != 0: print n n -= 1 else: print “what the…” 12 Answers 12
This was an interview question asked by a senior manager. Which is faster? while(1) { // Some code } or while(2) { //Some code } I said that both have the same execution speed, as the expression inside while should finally evaluate to true or false. In this case, both evaluate to true and there … Read more
What is wrong with using feof() to control a read loop? For example: #include <stdio.h> #include <stdlib.h> int main(int argc, char **argv) { char *path = “stdin”; FILE *fp = argc > 1 ? fopen(path=argv[1], “r”) : stdin; if( fp == NULL ){ perror(path); return EXIT_FAILURE; } while( !feof(fp) ){ /* THIS IS WRONG */ … Read more
I am having trouble coming up with the right combination of semicolons and/or braces. I’d like to do this, but as a one-liner from the command line: while [ 1 ] do foo sleep 2 done 14 s 14 while true; do foo; sleep 2; done By the way, if you type it as a … Read more
I need to emulate a do-while loop in a Python program. Unfortunately, the following straightforward code does not work: list_of_ints = [ 1, 2, 3 ] iterator = list_of_ints.__iter__() element = None while True: if element: print element try: element = iterator.next() except StopIteration: break print “done” Instead of “1,2,3,done”, it prints the following output: … Read more
When is while(true) true, and when is it false? It’s always true, it’s never false. Some people use while(true) loops and then use break to exit them when a certain condition is true, but it’s generally quite sloppy practice and not recommended. Without the use of break, return, System.exit(), or some other such mechanism, it will keep looping forever.
Use a while loop above input line as: And, use if condition to break. Also, condition for leap year is wrong in your code. It should be: if((year % 100 == 0 && year % 400 == 0) || (year % 4 == 0 && year % 100 != 0)) //its a leap year else … Read more
Use break: while (true) { …. if (obj == null) { break; } …. } However, if your code looks exactly like you have specified you can use a normal while loop and change the condition to obj != null: while (obj != null) { …. }
(I have a homework question that I’ve been stuck on that concerns “do-while loops” in Java. ) It is asking me to have a do-while loop that continues to prompt a user to enter a “number less than 100”, up until the entered number is actually less than 100. (It will run three tests:) Ex: … Read more
