goto | 易学教程

Will using goto leak variables?

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Is it true that goto jumps across bits of code without calling destructors and things? e.g. void f() { int x = 0; goto lol; } int main() { f(); lol: return 0; } Won't x be leaked? Lightness Races in Orbit Warning: This answer pertains to C++ only ; the rules are quite different in C. Won't x be leaked? No, absolutely not. It is a myth that goto is some low-level construct that allows you to override C++'s built-in scoping mechanisms. (If anything, it's longjmp that may be prone to this.) Consider the following mechanics that prevent you from doing "bad things" with labels (which includes case

Does anyone still use [goto] in C# and if so why? [closed]

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问题 I was wondering whether anyone still uses the \"goto\" keyword syntax in C# and what possible reasons there are for doing so. I tend to view any statements that cause the reader to jump around the code as bad practice but wondered whether there were any credible scenarios for using such a syntax? Goto Keyword Definition 回答1: There are some (rare) cases where goto can actually improve readability. In fact, the documentation you linked to lists two examples: A common use of goto is to transfer

Use GOTO or not? [closed]

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问题 Currently I am working on a project where goto statements are heavely used. The main purpose of goto statements is to have one cleanup section in a routine rather than multiple return statements. Like below: BOOL foo() { BOOL bRetVal = FALSE; int *p = NULL; p = new int; if (p == NULL) { cout<<\" OOM \\n\"; goto Exit; } // Lot of code... Exit: if(p) { delete p; p = NULL; } return bRetVal; } This makes it much easier as we can track our clean up code at one section in code, that is, after the

How can I use goto in Javascript?

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问题 I have some code that I absolutely must implement using goto . For example, I want to write a program like this: start: alert(\"RINSE\"); alert(\"LATHER\"); repeat: goto start Is there a way to do that in Javascript? 回答1: Absolutely! There is a project called Summer of Goto that allows you use JavaScript at its fullest potential and will revolutionize the way you can write your code. This JavaScript preprocessing tool allows you to create a label and then goto it using this syntax: [lbl]

Alternative to a goto statement in Java

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问题 What is an alternative function for the goto keyword in Java? Since Java does not have a goto. 回答1: You could use a labeled BREAK statement: search: for (i = 0; i < arrayOfInts.length; i++) { for (j = 0; j < arrayOfInts[i].length; j++) { if (arrayOfInts[i][j] == searchfor) { foundIt = true; break search; } } } However, in properly designed code, you shouldn't need GOTO functionality. 回答2: There isn't any direct equivalent to the goto concept in Java. There are a few constructs that allow you

Is there a “goto” statement in bash?

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问题 Is there a \"goto\" statement in bash ? I know It is considered bad practice, but I need specifically \"goto\". 回答1: No, there is not; see §3.2.4 "Compound Commands" in the Bash Reference Manual for information about the control structures that do exist. In particular, note the mention of break and continue , which aren't as flexible as goto , but are more flexible in Bash than in some languages, and may help you achieve what you want. (Whatever it is that you want . . .) 回答2: If you are

(Windows batch) Goto within if block behaves very strangely

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问题 If I take the following Windows batch code snippet and run it: echo foo if 1 == 1 ( echo bar goto asdf :asdf echo baz ) else ( echo quux ) The output I would expect is: foo bar baz But instead I get: foo bar baz quux If I comment out the goto asdf line, it gives the output I expect. The echo quux line should never be exectuted, so why is the existence of the goto causing that to happen? UPDATE: For what it\'s worth, here\'s a workaround that correctly does what I originally intended: goto

Is using a 'goto' statement bad?

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问题 After doing some reseach on how to break through a secondary loop while (true) { // Main Loop for (int I = 0; I < 15; I++) { // Secondary loop // Do Something break; // Break main loop? } } most people recommended to call the \'goto\' function Looking as the following example: while (true) { // Main Loop for (int I = 0; I < 15; I++) { // Secondary Loop // Do Something goto ContinueOn; // Breaks the main loop } } ContinueOn: However; I have often heard that the \'goto\' statement is bad

Is there a label/goto in Python?

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问题 Is there a goto or any equivalent in Python to be able to jump to a specific line of code? 回答1: No, Python does not support labels and goto, if that is what you're after. It's a (highly) structured programming language. 回答2: Python offers you the ability to do some of the things you could do with a goto using first class functions. For example: void somefunc(int a) { if (a == 1) goto label1; if (a == 2) goto label2; label1: ... label2: ... } Could be done in python like this: def func1(): ...

Is there a goto statement in Java?

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问题 I\'m confused about this. Most of us have been told that there isn\'t any goto statement in Java. But I found that it is one of the keywords in Java. Where can it be used? If it can not be used, then why was it included in Java as a keyword? 回答1: The Java keyword list specifies the goto keyword, but it is marked as "not used". It was in the original JVM (see answer by @VitaliiFedorenko), but then removed. It was probably kept as a reserved keyword in case it were to be added to a later