Need to replace arrays with strings

Question

I have this string: CO2 + H2O + XO

And I am going for this: CO2 + H2O + NaO.

I have researched this quite a bit and I am at a loss on what to do with a mixture of strings and arrays.

$reactant = 'CO2 + H2O + XO';

$products = str_split($reactant);

foreach ($products as $splitresult)
{
  $splitresult = str_replace('X', 'Na', $splitresult); 
}

echo $splitresult;

do you want to replace all the X's as 'Na' or only when they are next to 'O' ? I ask because as you are working with elements there are other(s) elements including an X as far as I remember, and if you are putting this as just an example and it's not the real scenario specify as much as possible so we can work out something accurate. — aleation
– aleation, Commented Dec 16, 2013 at 9:09
Ok, so when you say X in string you mean $someElement. This is handled very easily with str_replace($searchFor, $replaceWith, $subject) — hanzo2001
– hanzo2001, Commented Dec 16, 2013 at 9:09
I am working on decomposition reactions. On this specific one, i don't know the metals and i use place holders i.e X. It only covers upto AP level, so i don't expect anyone looking for X or Y elements. Str_split also seems to work better than explode. — Edwinner
– Edwinner, Commented Dec 16, 2013 at 9:19
@Edwinner can I ask why str_split works better than explode for you? — Ryan
– Ryan, Commented Dec 16, 2013 at 9:36

John Allen · Accepted Answer · 2013-12-16 08:53:37Z

2

echo str_replace('X', 'Na', $reactant) ;

answered Dec 16, 2013 at 8:53

John Allen

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Ryan · Accepted Answer · 2013-12-16 08:53:50Z

2

If you're always going to be joining the elements up with a plus sign, you could explode the string as so:

$parts = explode(' + ', $reactant);

Then loop around the array

foreach($parts as &$part) {
    $part = str_replace('X', 'Na', $part);
}

Then to display the results, implode the array back together using the plus:

$reactant = implode(' + ', $parts);

answered Dec 16, 2013 at 8:53

Ryan

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Comments

Thibault · Accepted Answer · 2013-12-16 08:56:46Z

1

What about just this :

<?php
 $reactant = 'CO2 + H2O + XO';
 $reactant = str_replace('X', 'Na', $reactant);
?>

If you really want to split because your code is longer, you have to set via the key, because the $splitresult will be overwritten after each loop pass. It's a temporary variable. Here is the right way to do it :

<?php
 $reactant = 'CO2 + H2O + XO';
 $products = str_split($reactant);

 foreach($products as $i=>$splitresult)
 {
  $products[$i] = str_replace('X', 'Na', $splitresult) ;
 }
 $reactant = implode('',$products);
?>

answered Dec 16, 2013 at 8:56

Thibault

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Comments

Seeinyou · Accepted Answer · 2013-12-16 08:58:42Z

0

<?php
$reactant = 'CO2 + H2O + XO';
$products = explode($reactant, ' + ');

foreach($products as $key => $splitresult)
{
    $products[ $key ] = str_replace('X', 'Na', $splitresult);
}
print_r( $products );

answered Dec 16, 2013 at 8:58

Seeinyou

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