Concatenating a variable name with another variable

toodi4

I have a query set up to pull data, and then I run a while loop to loop through the data. It's very basic, so I won't repeat that part of the coding here. But lets say the data fields are.

$month
$day
$property_name
$comments

$month and $day are integers, and I'm try to get the data to populate a calender.

So I could set it up like this:

if ($day == 1) {
$sales_date1 = "$propery_name: $comments";
}
else
{
$sales_date1 = "";
}

And I could repeat this for every day of the month, but this would seem ridiculous. The more logical way would be to have one line of code with the day concatenated onto the variable.

$sales_date$day = "$propery_name: $comments";

But obviously the above won't work. I'm trying to get $day to be expressed as a the number which is pulled from that particular row, so if $day = 1 for that particular row, it would actually be

$sales_date1 = "$propery_name: $comments"

I know this is a very basic syntax question, but I can't find any reference for how to do this.

laserlight

You could use variable variables, but why not use an array?

toodi4

laserlight wrote:
You could use variable variables, but why not use an array?

Probably because arrays are my weakness. 🙂

Right now, if I could just get that one line of code, everything would be solved.

laserlight

Probably because arrays are my weakness.

You should start learning to use them, or you will find yourself very weak.

Right now, if I could just get that one line of code, everything would be solved.

${'sales_date' . $day} = "$propery_name: $comments";

Bunkermaster

I suggest you study arrays before taking the habbit of using something that will render your code totally unmaintainable.

toodi4

Point taken. I'm not trying to avoid arrays completely or anything, but how would you attack this particular problem with an array and why would it work better?

laserlight

Compare:

${'sales_date' . $day} = "$propery_name: $comments";

with:

$sales_date[$day] = "$propery_name: $comments";

Not only that, but using variable variables means that you lose out on PHP's array functions, and related functions that use arrays.

Installer

For one simple example, sort these:

$var_1 = 7;
$var_2 = 8;
$var_3 = 6;

Now sort this (hint: sort()):

$var = array(7, 8, 6);

Weedpacket

And if you put all your sales dates into an array $sales_date[1], $sales_date[2], ...., you have one variable, $sales_date, that contains all your days and their properties/comments. If the advantages of that aren't obvious I don't know what is.

leatherback

toodi4 wrote:
Probably because arrays are my weakness.

Sounds to me you are a little afraid to take a jump into unknown water. I'll chart it out for you a little:

Look at an array as a collection box of variables. Say, I have a list of 3 variables:

$var1 = 'apple';
$var2 = 'pear';
$var3 = 'cherry';

Now, if I ask you to show the value of $var2, you have no trouble: echo $var2, which will display pear.

So.. Now I do the same, but I place them in an array:

$var = array(
1 => 'apple',
2 => 'pear',
3 => 'cherry');

Again, I ask you for the second value in the array. This sounds complex. But the nice thing is, you can directly refer to the second VALUE, by using the KEY. Whooo! Stop, I hear you say.. What is the key?

Here goes:
An array consists of the variable name (Here: var), and a number of combinations of KEYs and VALUEs, here the 1; 2; 3 and 'apple', 'pear', 'cherry'. The key identifies 'where' the VALUE is stored in the array. You indicate this with straight brackets:

the value of key 2 is: $var[2], which you can display just like before: echo $var[2].

Of course often you do not want to define the keys. In that caase you can just say:

$ var = array('apple', 'pear', 'cherry');

Please note, that then the keys start at 0! So:
echo $var[2] will display cheery (!)

You can also use strings as a key, and/or use the brackets to set specific key/value combinations:
$vars['type'] = 'fruit';

If you want to display every single variable of an array:

for($var = $key=>$value)
  {
  echo $key.": ".$value;
  }

  // Note that the expression in the foreach only tells you how you want to refer to the KEY and the VALUE. You could also use $string=>$paper, or whatever you prefer, and get exactly the same result:
for($var = $string=>$paper)
  {
  echo $string.": ".$paper;
  }

to see the structure & values of an array:
print_r($var);
Note: print_r does not generate HTML, so view the source of your page, or add <pre> </pre> tags to see the structure. Else you see a mumble-jumble string of text.

I hope it helps to get you going.