Goto top in php

goto

The goto operator can be used to jump to another section in the program. The target point is specified by a case-sensitive label followed by a colon, and the instruction is given as goto followed by the desired target label. This is not a full unrestricted goto . The target label must be within the same file and context, meaning that you cannot jump out of a function or method, nor can you jump into one. You also cannot jump into any sort of loop or switch structure. You may jump out of these, and a common use is to use a goto in place of a multi-level break .

Example #1 goto example

 goto a; echo 'Foo'; a: echo 'Bar'; ?>

The above example will output:

Example #2 goto loop example

 for($i=0,$j=50; $i100; $i++) < while($j--) < if($j==17) goto end; > > echo "i = $i"; end: echo 'j hit 17'; ?>

The above example will output:

Example #3 This will not work

 goto loop; for($i=0,$j=50; $i100; $i++) < while($j--) < loop: >> echo "$i = $i"; ?>

The above example will output:

Fatal error: 'goto' into loop or switch statement is disallowed in script on line 2 

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Php how to write goto statement in php

If the purpose of using GOTOs is to make breaking out of multiply nested loops more efficient there’s a better way: labelled code blocks and break statements that can reference labels: Now is is clear which loop/block to exit, and the exit is structured; you can’t get spaghetti code with this like you can with real gotos. Generally, goto statement comes in the script as a part of conditional expression such as if, else or case (in switch construct) Syntax After statement2, if expression (as a part of if statement) is true, program flow is directed to label1 .

PHP goto Statement

Introduction

The goto statement is used to send flow of the program to a certain location in the code. The location is specified by a user defined label. Generally, goto statement comes in the script as a part of conditional expression such as if, else or case (in switch construct)

Syntax

statement1; statement2; if (expression) goto label1; statement3; label1: statement4;

After statement2, if expression (as a part of if statement) is true, program flow is directed to label1 . If it is not true, statement3 will get executed. Program continues in normal flow afterwards.

In following example, If number input by user is even, program jumps to specified label

Example

Output

This will produce following result −

The label in front of goto keyword can appear before or after current statement. If label in goto statement identifies an earlier statement, it constitutes a loop.

Foolowing example shows a loop constructed with goto statement

Example

Output

This will produce following result −

Using goto, program control can jump to any named location. However, jumping in the middle of a loop is not allowed.

Example

Output

This will produce following result −

PHP Fatal error: 'goto' into loop or switch statement is disallowed in line 5

PHP and the goto statement to be added in PHP 5.3, I’m wondering: what can this do to make my code more well-organized? How can I implement this in larger projects, without screwing it up. Since

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The reason I did not talk about the goto statement is that it just makes code harder to maintain
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Use goto inside function php

You cannot goto outside of a function I believe: http://php.net/manual/en/control-structures.goto.php

Direct Quote: This is not a full unrestricted goto. The target label must be within the same file and context, meaning that you cannot jump out of a function or method, nor can you jump into one.

This might have to do with the fact that php is parsed and jumping out of a function will cause a memory leak or something because it was never properly closed. Also as everyone else said above, really you don’t need a goto. You can just return different values from the function and have a condition for each. Goto is just super bad practice for modern coding (acceptable if you are using basic).

function foo(a) < if (a==1) < return 1; >elseif (a==3) < return 2; >else < return 3; >> switch (foo(4)) < //easily replaceable with elseif chain case 1: echo 'Foo was 1'; break; //These can be functions to other parts of the code case 2: echo 'Foo was 3'; break; case 3: echo 'Foo was not 1 or 3'; >

There’s no way to jump in or out of a function. But since you state that you need it, here’s an alternative route.

function myFunction() < if (condition) < return true; >return false; > someLine: // . $func = myFunction(); if($func == true) goto someLine; 

As previously stated you can’t. As for «I need it», I highly doubt this. Whatever code you have at someLine: can easily be made into a function that you can call from the other if needed.

I’m about to use a goto statement, while (condition) < if ($this->phase1() || $this->phase2() || $this->phase3() || $this->phase4()) < // Success! >>.

GOTO command in PHP?

They are not adding a real GOTO, but extending the BREAK keyword to use static labels. Basically, it will be enhancing the ability to break out of switch nested if statements. Here’s the concept example I found:

 echo "not shown"; blah: echo "iteration $i\n"; > ?> 

Of course, once the GOTO «rumor» was out, there was nothing to stop some evil guys to propagate an additional COMEFROM joke. Be on your toes.

I’m always astonished at how incredibly dumb the PHP designers are. If the purpose of using GOTOs is to make breaking out of multiply nested loops more efficient there’s a better way: labelled code blocks and break statements that can reference labels:

Now is is clear which loop/block to exit, and the exit is structured; you can’t get spaghetti code with this like you can with real gotos.

This is an old, old, old idea. Designing good control flow management structures has been solved since the 70s, and the literature on all this is long since written up. The Bohm-Jacopini theorem showed that you could code anything with function call, if-then-else, and while loops. In practice, to break out of deeply nested blocks, Bohm-Jacopini style coding required extra boolean flags («set this flag to get out of the loop») which was clumsy coding wise and inefficient (you don’t want such flags in your inner loop). With if-then-else, various loops (while,for) and break-to-labelled block, you can code any algorithm without no loss in efficiency. Why don’t people read the literature, instead of copying what C did? Grrr.

Granted, I am not a PHP programmer, and I don’t know what PHP’s exact implementation of GOTO will look like, but here is my understanding of GOTO:

GOTO is just a more explicit flow control statement like any other. Let’s say you have some nested loops and you only need to find one thing. You can put in a conditional statement (or several) and when conditions are met properly, you can use a GOTO statement to get out of all the loops, (instead of having a ‘break’ statement at each level of nesting with a conditional statement for each. And yes, I believe the traditional implementation is to have named labels that the GOTO statement can jump to by name. You can do something like this:

This is a simpler (and more efficient) implementation than without GOTO statements. The equivalent would be:

for(. ) < for (. ) < for (. ) < // some code if (x) break; >if(x) break; > if(x) break; > 

In the second case (which is common practice) there are three conditional statements, which is obviously slower than just having one. So, for optimization/simplification reasons, you might want to use GOTO statements in tightly nested loops.

Real goto usage in PHP, I could have added in IFELSE statement blocks to achieve the same results, but the amount of logic in the script (and the amount of nested IF

Php goto variable

Goto works only like this

but yours one is impossible

_{Yes, I know using goto is discouraged, but an answer to the actual question is a lot better than these saying DO NOT USE GOTO GOTO IS EVIL}

Addendum: eval goto

It’s not likely you really want to do that:

The only way I could see this working is if you do this:

• This may not work at all (I don’t have a 5.3 install readily available to test it)
• eval() should be avoided at all costs under 99.9% of circumstances
• Ditto goto . It is rarely the answer — if you find yourself using goto’s, you would probably do better to examine the structure of your code.

Most of the time, people use goto to avoid a messy if-else structure, but there is something (slightly) nicer that you can do, which achieves the same thing: wrap the code block in do <> while (FALSE); . This means you can call break to skip the rest of the code block and jump straight to the end. These can also be nested, so you can call break 2; etc to skip to the right point.

I know there are many people who will disagree with me on this approach — let the abuse storm begin.

Don’t do it with goto, even if it is possible. Do it this way instead:

$goto = 'end'; $goto(); function end()

You can also do this in an object context using $this->$goto() — very handy sometimes.

PHP goto alternative, What would you suggest then? · mixing logic (retrieve from database) with html output is a bad practice as well. · I dont know what ur script

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Goto top in php

Блог веб разработки статьи | видеообзоры | исходный код

goto php

Всем привет! Сегодня мы с вами познакомимся с метками в php c помощью которых мы можем перемещаться в заданную часть программы. Поехали!

Для того чтобы создать метку нам достаточно указать ее название и поставить двоеточие.

echo "Привет мир"; echo "
"; flag: echo "hello world";

Нам выведется две строчки «Привет мир» и «hello world». Здесь мы создали метку с названием flag. И теперь чтобы ей воспользоваться нам достаточно указать оператор goto и название метки.

goto flag; echo "Привет мир"; echo "
"; flag: echo "hello world";

В результате нам выведется только одна строчка «hello world». Потому что как только мы доходим до оператора goto мы автоматически перемещаемся в указанную метку. То есть в нашем случае это flag.

Заметьте что я вызвал метку до ее инициализации, это тоже очень важный нюанс. Если мы попробуем сначала создать метку, а потом ее вызвать у нас произойдет зацикливание.

flag: echo "hello world"; goto flag;

Так как мы снова и снова будем возвращаться в заданную часть программы где эта метка будет вызываться каждый раз.

Конечно мы можем на вызов метки навесить условие.

Здесь у нас получилось подобие цикла который выводит числа от одного до десяти. Но так делать не рекомендуется, потому что не во всех ситуациях это отрабатывает корректно.

Еще нельзя вызывать меток которых не указано:

goto flag; echo "Привет мир";

Здесь мы совершаем переход к метке flag. Однако в нашей программе она не указана, в результате чего произойдет ошибка.

C помощью меток мы можем выходить из циклов. Причем в заданную часть программы.

$n = 0; for($i=-10;$i $n++; > end: echo $n;

Когда у нас значение переменной $i в цикле стало равняться нулю, мы из него вышли и вывели количество отработанных итераций.

Еще вы должны понимать что мы не можем вызывать метку которая находится в функции за ее пределами.

goto start; echo 'текст'; function hello() < start: echo 'Привет'; >hello();

Результатом у нас будет ошибка.

На этом дорогие друзья данная статья подошла к концу. Если что то было непонятно оставляйте свои вопросы в комментариях или группе

Ну а я с вами прощаюсь. Желаю успехов и удачи! Пока!

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