field value through variable name 1

[zianole]

How can i access a field value through variable name

for example
if id is database table column then through

$row->id;

i can get its value but if i want to use a variable like

$var="id";
$row->anyfunction($var);
is there a way to to this?

 

[sleipnir214]

PHP supports something called "variable variables" and they can, at least with PHP 5, be used with object instantiations, too.

This script:

<?php

class foo
{
	var $bar = 'baz';
}

$a = new foo();

$b = 'bar';

print $a->{$b};
?>

Outputs:

[tt]baz[/tt]



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[zianole]

Thanks sleipnir214!
I tested, its working in my php version.

Can I ask, how can i loop all variables (properties)?

I tried following code but an error raised

for($b=0; $b<=5; $b++{
echo $a->{$b};
}

instead of providing name ($b = 'bar' I tried to use number ($b = 1 but php raised an error on ($a->{$b}

thanks

 

[sleipnir214]

I doubt what you are trying to do will work, simply because [tt]$1[/tt] is not a valid PHP label. The PHP manual entry which introduces variables reads, in part:

Variable names follow the same rules as other labels in PHP. A valid variable name starts with a letter or underscore, followed by any number of letters, numbers, or underscores.

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[Kozusnik]

I'd do something like...

$query = "SELECT id, whatever";
$result = mysql_query($query) or die( mysql_error());

$i=0;
while ($rows = mysql_fetch_row($result)){
$id[$i] = $rows[0];
$i++;
}

You may be using a different database, or you may use...
$i=0;
foreach ($rows as $row){
$id[$i] = $row['id'];
$i++;
}

Play with it and see what works best.

Mark

 

[zianole]

Actually i was looking for to loop every column (field) of feched database row without directly pointing the name of field. for example in above Kozusnik example,

$i=0;
foreach ($rows as $row){
$id[$i] = $row['id'];
$i++;
}

Is it possible to loop every field of every row (nested loop).

$i=0;
foreach ($rows as $row){
// assumed
// somethin like this
foreach ($column in $row){
echo $row[$column];
$i++;
}
}

and output should be each column value of each row. a tabular form.


I think I am unable to explain my problem. I write it in different way.

I have a query.
$query = "SELECT * From table12";

Now I want to display all rows and values of table2, but I don't know exactly how many columns/fields (and their names) are in table2

 

[sleipnir214]

I would do something like:

$a = mysql_query("SELECT * FROM some_table");

while ($row = mysql_fetch_assoc($a))
{
foreach ($row as $value)
{
print $value;
print "\t";
}
print "\r\n";
}


You can easily change this snippet to output the necessary HTML tags to format the output in a table.

You could also, between the mysql_fetch_assoc() invocation the the beginning of the while-loop add an initial row fetch and loop to output column headers that match column names:

$a = mysql_query(".....");

$row = mysql_fetch_assoc();
foreach ($row as $columnname => $columnvalue)
{
print $columnname;
print "\t";
}
print "\r\n";

foreach ($row as $value)
{
print $value;
print "\t";
}

while (......)
.
.
.

Again, it's not too hard to hang the output of HTML tags to format this as an HTML table.



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[zianole]

thanks again sleipnir214!
That was the actual solution i was looking for. and Sorry! I could not explain actual problem in start of thread.

also thanks Kozusnik! his example helped me, how to put values of single column in array, for all rows.


Zianole

 

[sleipnir214]

The answer I posted is duplicated as sample code on the pages of the PHP online manual. I strongly recommend that you make yourself familiar with it:

http://www.php.net/docs.php

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