Re: [PHP] Rewind foreach loop
On Fri, 2007-11-30 at 14:46 -0500, Robert Cummings wrote:
This is dangerous use of the array functions. A problem occurs when you
have a value that evaluates to false (such as the first entry in the
example array :). In fact the only way to ensure you traverse the array
properly is to use each() since it returns an array except when no more
entries exist. Also you want to reset() the array before looping
(normally anyways).
?php
reset( $data );
while( ($entry = each( $data )) )
{
// ...
if( $errorCondition )
{
prev( $data );
continue;
}
next( $data );
Newbie bug!! Newbie bug!! each() advances the array pointer so don't do
a next() call :)
Cheers,
Rob.
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Re: [PHP] Rewind foreach loop
On Fri, 2007-11-30 at 09:51 -0800, Jim Lucas wrote:
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I encounter
and
error in a foreach loop, I need the ability to rewind the array pointer by
one. How can I achieve this?
regards,
Jeffery
No, you can't rewind the array. Foreach makes a copy of the array, and works
off that copy.
You might need to look into using do...while() instead
Something thing like this should work.
?php
$row = current($your_array); Gives you the first element in $your_array
do {
...
work with your $row...
determine if their is an error
...
if ( $error ) {
# Watch out for infinite loop
# maybe have a counter that increments each time it rewinds
$your_array
#and have it stop at 10 loops or something.
prev($your_array);
}
} while( $row = next($your_array) );
?
This is dangerous use of the array functions. A problem occurs when you
have a value that evaluates to false (such as the first entry in the
example array :). In fact the only way to ensure you traverse the array
properly is to use each() since it returns an array except when no more
entries exist. Also you want to reset() the array before looping
(normally anyways).
?php
reset( $data );
while( ($entry = each( $data )) )
{
// ...
if( $errorCondition )
{
prev( $data );
continue;
}
next( $data );
}
?
Cheers,
Rob.
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Re: [PHP] Rewind foreach loop
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I encounter and
error in a foreach loop, I need the ability to rewind the array pointer by
one. How can I achieve this?
regards,
Jeffery
No, you can't rewind the array. Foreach makes a copy of the array, and works
off that copy.
You might need to look into using do...while() instead
Something thing like this should work.
?php
$row = current($your_array); Gives you the first element in $your_array
do {
...
work with your $row...
determine if their is an error
...
if ( $error ) {
# Watch out for infinite loop
# maybe have a counter that increments each time it rewinds
$your_array
#and have it stop at 10 loops or something.
prev($your_array);
}
} while( $row = next($your_array) );
?
This way, you are working on the only copy of $your_array
--
Jim Lucas
Some men are born to greatness, some achieve greatness,
and some have greatness thrust upon them.
Twelfth Night, Act II, Scene V
by William Shakespeare
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Re: [PHP] Rewind foreach loop
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
this might give you an[other] idea ... note it's
an infinite loop - watch out for those.
do {
foreach (array(0,1,2,3,4,5,6,7,8,9,10) as $k = $v) {
if ($v == 5) continue 2;
echo $v, PHP_EOL;
}
} while (true);
The above doesn't seem to work. In one of my scenarios, when I encounter and
error in a foreach loop, I need the ability to rewind the array pointer by
one. How can I achieve this?
regards,
Jeffery
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Re: [PHP] Rewind foreach loop
I think the best option for me is to refactorise my code a bit to cater to my
situation. Thanks all for your help.
Jeffery
On Fri, 30 Nov 2007 02:32:11 pm Jeffery Fernandez wrote:
On Fri, 30 Nov 2007 02:13:52 pm Chris wrote:
Jeffery Fernandez wrote:
On Fri, 30 Nov 2007 02:01:47 pm Chris wrote:
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I
encounter and error in a foreach loop, I need the ability to rewind
the array pointer by one. How can I achieve this?
echo $numbers[$index-1] . PHP_EOL;
That will only give me the value of the previous index. What I want is
to rewind the array pointer and continue with the loop.
and you're going to be in an endless loop then.. because each time it
gets rewound, it gets the same key again and rewinds and ...
No, I am only rewinding if there is an error. Then I have the script
auto-learning from the error, fix a config file and then want to go back to
the array pointer to re-execute the process.
You could do it with a for or while loop probably.
Thats what I am looking at now.
What are you trying to achieve? Maybe there's an alternative.
As mentioned above.
cheers,
Jeffery
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Australia
web: http://www.ivt.com.au
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Re: [PHP] Rewind foreach loop
$keys = array_values($array);
for ($i=0; $icount($keys); $i++) {
if ($keys[$i] == 5)
$i -= 2;
}
Untested, but should work.
On Nov 29, 2007, at 7:13 PM, Chris [EMAIL PROTECTED] wrote:
Jeffery Fernandez wrote:
On Fri, 30 Nov 2007 02:01:47 pm Chris wrote:
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I
encounter
and error in a foreach loop, I need the ability to rewind the array
pointer by one. How can I achieve this?
echo $numbers[$index-1] . PHP_EOL;
That will only give me the value of the previous index. What I want
is to rewind the array pointer and continue with the loop.
and you're going to be in an endless loop then.. because each time
it gets rewound, it gets the same key again and rewinds and ...
You could do it with a for or while loop probably.
What are you trying to achieve? Maybe there's an alternative.
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Re: [PHP] Rewind foreach loop
At 2:11 PM +1100 11/30/07, Jeffery Fernandez wrote:
On Fri, 30 Nov 2007 02:01:47 pm Chris [EMAIL PROTECTED] wrote:
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I encounter
and error in a foreach loop, I need the ability to rewind the array
pointer by one. How can I achieve this?
echo $numbers[$index-1] . PHP_EOL;
That will only give me the value of the previous index. What I want is to
rewind the array pointer and continue with the loop.
I would think that if you rewound the array pointer as above, you'd
simply end up in an infinite loop, as you'd keep hitting the
condition that triggered the rewind. So I'm assuming you have some
other test in there and this is just a stripped down example.
If you're using a one-dimensional array, as opposed to a
multidimensional and/or associative array, you can do (untested):
$Count = count($numbers);
for ($i=0; $i$Count; $i++) {
$value = $numbers[$i];
if ($value == 5 some_other_test()) {
$value = $numbers[--$i];
}
echo Value: $value . PHP_EOL;
}
Wouldn't be much more complex to extend to a multidimensional array
with an integer index. If you were using an associative array with a
string index, you'd probably have to do something like
$NotJustNumbers = array('a'='slurm', 'b'='fry', 'c'='leela');
$Keys = array_keys($NotJustNumbers);
$Count = count($Keys);
for ($i=0; $i$Count; $i++) {
$value = $NotJustNumbers[$Keys[$i]];
if ($value == 5 some_other_test()) {
$value = $NotJustNumbers[$Keys[--$i]];
}
echo Value: $value . PHP_EOL;
}
- steve
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+ said t e lawrence, picking up his fork +
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Re: [PHP] Rewind foreach loop
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I encounter and
error in a foreach loop, I need the ability to rewind the array pointer by
one. How can I achieve this?
echo $numbers[$index-1] . PHP_EOL;
Of course that assumes that the value you're looking for isn't the first
element :)
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Re: [PHP] Rewind foreach loop
On Fri, 30 Nov 2007 02:01:47 pm Chris wrote:
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I encounter
and error in a foreach loop, I need the ability to rewind the array
pointer by one. How can I achieve this?
echo $numbers[$index-1] . PHP_EOL;
That will only give me the value of the previous index. What I want is to
rewind the array pointer and continue with the loop.
Of course that assumes that the value you're looking for isn't the first
element :)
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http://www.designmagick.com/
--
Internet Vision Technologies
Level 1, 520 Dorset Road
Croydon
Victoria - 3136
Australia
web: http://www.ivt.com.au
phone: +61 3 9723 9399
fax: +61 3 9723 4899
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Re: [PHP] Rewind foreach loop
Jeffery Fernandez wrote:
On Fri, 30 Nov 2007 02:01:47 pm Chris wrote:
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I encounter
and error in a foreach loop, I need the ability to rewind the array
pointer by one. How can I achieve this?
echo $numbers[$index-1] . PHP_EOL;
That will only give me the value of the previous index. What I want is to
rewind the array pointer and continue with the loop.
and you're going to be in an endless loop then.. because each time it
gets rewound, it gets the same key again and rewinds and ...
You could do it with a for or while loop probably.
What are you trying to achieve? Maybe there's an alternative.
--
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Re: [PHP] Rewind foreach loop
On Fri, 30 Nov 2007 02:13:52 pm Chris wrote:
Jeffery Fernandez wrote:
On Fri, 30 Nov 2007 02:01:47 pm Chris wrote:
Jeffery Fernandez wrote:
Hi all,
Is it possible to rewind a foreach loop? eg:
$numbers = array(0,1,2,3,4,5,6,7,8,9,10);
foreach ($numbers as $index = $value)
{
if ($value == 5)
{
prev($numbers);
}
echo Value: $value . PHP_EOL;
}
The above doesn't seem to work. In one of my scenarios, when I
encounter and error in a foreach loop, I need the ability to rewind the
array pointer by one. How can I achieve this?
echo $numbers[$index-1] . PHP_EOL;
That will only give me the value of the previous index. What I want is to
rewind the array pointer and continue with the loop.
and you're going to be in an endless loop then.. because each time it
gets rewound, it gets the same key again and rewinds and ...
No, I am only rewinding if there is an error. Then I have the script
auto-learning from the error, fix a config file and then want to go back to
the array pointer to re-execute the process.
You could do it with a for or while loop probably.
Thats what I am looking at now.
What are you trying to achieve? Maybe there's an alternative.
As mentioned above.
cheers,
Jeffery
--
Postgresql php tutorials
http://www.designmagick.com/
--
Internet Vision Technologies
Level 1, 520 Dorset Road
Croydon
Victoria - 3136
Australia
web: http://www.ivt.com.au
phone: +61 3 9723 9399
fax: +61 3 9723 4899
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