It’s not that i– is faster than i++. Actually, they’re both equally fast. What takes time in ascending loops is evaluating, for each i, the size of your array. In this loop: for(var i = array.length; i–;) You evaluate .length only once, when you declare i, whereas for this loop for(var i = 1; i … Read more
until passwd do echo “Try again” done or while ! passwd do echo “Try again” done
Here’s the working version of the code in question (requires at least version Matplotlib 1.1.0 from 2011-11-14): import numpy as np import matplotlib.pyplot as plt plt.axis([0, 10, 0, 1]) for i in range(10): y = np.random.random() plt.scatter(i, y) plt.pause(0.05) plt.show() Note the call to plt.pause(0.05), which both draws the new data and runs the GUI’s … Read more
The else clause is only executed when your while condition becomes false. If you break out of the loop, or if an exception is raised, it won’t be executed. One way to think about it is as an if/else construct with respect to the condition: if condition: handle_true() else: handle_false() is analogous to the looping … Read more
Both loops are infinite, but we can see which one takes more instructions/resources per iteration. Using gcc, I compiled the two following programs to assembly at varying levels of optimization: int main(void) { while(1) {} return 0; } int main(void) { while(2) {} return 0; } Even with no optimizations (-O0), the generated assembly was … Read more
TL;DR while(!feof) is wrong because it tests for something that is irrelevant and fails to test for something that you need to know. The result is that you are erroneously executing code that assumes that it is accessing data that was read successfully, when in fact this never happened. I’d like to provide an abstract, … Read more
while true; do foo; sleep 2; done By the way, if you type it as a multiline (as you are showing) at the command prompt and then call the history with arrow up, you will get it on a single line, correctly punctuated. $ while true > do > echo “hello” > sleep 2 > … Read more
I am not sure what you are trying to do. You can implement a do-while loop like this: while True: stuff() if fail_condition: break Or: stuff() while not fail_condition: stuff() What are you doing trying to use a do while loop to print the stuff in the list? Why not just use: for i in … Read more