Many Python programmers are probably unaware that the syntax of while loops and for loops includes an optional else: clause: for val in iterable: do_something(val) else: clean_up() The body of the else clause is a good place for certain kinds of clean-up actions, and is executed on normal termination of the loop: I.e., exiting the … Read more
I want to write a Bash script to process text, which might require a while loop. For example, a while loop in C: int done = 0; while(1) { … if(done) break; } I want to write a Bash script equivalent to that. But what I usually used and as all the classic examples I … Read more
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Question 1: Why does the following code compile without having a return statement? public int a() { while(true); } Notice: If I add return after the while then I get an Unreachable Code Error. Question 2: On the other hand, why does the following code compile, public int a() { while(0 == 0); } even … Read more
I’ve heard this quite a few times. Are JavaScript loops really faster when counting backward? If so, why? I’ve seen a few test suite examples showing that reversed loops are quicker, but I can’t find any explanation as to why! I’m assuming it’s because the loop no longer has to evaluate a property each time … Read more
In the following program, if I set the variable $foo to the value 1 inside the first if statement, it works in the sense that its value is remembered after the if statement. However, when I set the same variable to the value 2 inside an if which is inside a while statement, it’s forgotten … Read more
Why does the following work fine? String str; while (condition) { str = calculateStr(); ….. } But this one is said to be dangerous/incorrect: while (condition) { String str = calculateStr(); ….. } Is it necessary to declare variables outside the loop? 20 Answers 20
I have a list consisting of like 20000 lists. I use each list’s 3rd element as a flag. I want to do some operations on this list as long as at least one element’s flag is 0, it’s like: my_list = [[“a”, “b”, 0], [“c”, “d”, 0], [“e”, “f”, 0], …..] In the beginning, all … Read more
I’ve heard this quite a few times. Are JavaScript loops really faster when counting backward? If so, why? I’ve seen a few test suite examples showing that reversed loops are quicker, but I can’t find any explanation as to why! I’m assuming it’s because the loop no longer has to evaluate a property each time … Read more
I have a script and want to ask the user for some information, but the script cannot continue until the user fills in this information. The following is my attempt at putting a command into a loop to achieve this but it doesn’t work for some reason: echo “Please change password” while passwd do echo … Read more
