PHP Array Losing Values Outside of Function

Question

Hey guys I have a weird problem trying to use a global array in php.

I don't even really want to use a global but here's what i'm trying to do.

I have 2 functions

createMatrix($name) which creates a 5x5 matrix of texts boxes and remembers values loadMatrix($name) which loads a 5x5 matrix from post data.

For some reason, after I run loadMatrix(), the values I set are lost in createMatrix()

I've tried a ton of debugging methods and declaring my matrix variables as globals but no luck. I know it's a scope issue because when I tried running everything outside of the functions it worked just fine.

<form action="Program4.php" method="post">
<?php
$matrixa = array(array());
$matrixb = array(array());
if($_POST['add'])
    echo "Add Clicked";
if($_POST['subtract'])
    echo "Subtract Clicked";
function loadArrays($name1,$name2) {
        //The Solution: global $matrixa, $matrixb;
    for($x = 0; $x < 5; $x++)
        for($y = 0; $y < 5; $y++) {
            $matrixa[$x][$y] = $_POST[$name1 . $x . $y];
            $matrixb[$x][$y] = $_POST[$name2 . $x . $y];
        }
}
function createMatrix($name) {
        //The Solution: global $matrixa, $matrixb;
    echo "<h2>" . $name . "</h2>\n";
    for($x = 0; $x < 5; $x++)
        echo $matrixa[0][$x];
    echo "<div style=\"border:ridge; border-width:7px; padding:12px; float:left; background-color:gray\">\n";
    for($x = 0; $x < 5; $x++) {
        for($y = 0; $y < 5; $y++) {
            echo "<input type=\"text\" name=\"" . $name . $x . $y . "\" maxlength=\"6\" style=\"width:50px\" value=\"";
            if($name == "MatrixA")
                echo "" . $matrixa[$x][$y];
            else if($name == "MatrixB")
                echo "" . $matrixb[$x][$y];
            echo "\">\n";
        }
        echo "<br>\n";
    }
    echo "</div>\n";
    echo "<br><br><br><br><br><br><br><br><br>\n";
}
loadArrays("MatrixA","MatrixB");
createMatrix("MatrixA");
createMatrix("MatrixB");
?>
<input type="submit" value="Add Matrices" name="add" />
<input type="submit" value="Subtract Matrices" name="subtract" />
</form>

This project is due at midnight so I'd appreciate some help :)

Basically the problem is trying to save the values. I am able to load the variables from post data into the arrays using loadArrays() just fine, but the values don't show up AT ALL when I use createMatrix();

I don't see you define loadMatrix() anywhere on your code. — Madara's Ghost
– Madara's Ghost, Commented Mar 16, 2012 at 19:49
Before using a global variable inside a function. Do this: global $matrixa; — Bjørne Malmanger
– Bjørne Malmanger, Commented Mar 16, 2012 at 19:49
You also forgot a ; at the end of loadMatrix("MatrixA","MatrixB") — Mattias
– Mattias, Commented Mar 16, 2012 at 19:51
I solved the problem right before I looked back. Bjorne Malmanger is right. I declared global $matrixa inside of each function and it worked like a charm. Thanks for the help guys! — user1274820
– user1274820, Commented Mar 16, 2012 at 19:54

Mattias · Accepted Answer · 2012-03-16 20:01:50Z

1

It looks like you need to use http://www.php.net/manual/en/reserved.variables.globals.php

You can use the $GLOBALS variable to get variables from the global scope

$GLOBALS['matrixa']

or the define variables with global before using it, then the $matrixa, $matrixb will refere to the global versions, more info here

function createMatrix() {
    global $matrixa, $matrixb;
}

edited Mar 16, 2012 at 20:01

answered Mar 16, 2012 at 19:54

Mattias

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1 Comment

user1274820 Over a year ago

To all you guys, thanks. loadMatrix() was supposed to be loadArrays() my bad I was going to try to change it to return some values or whatever but I was able to solve the problem like you have said. Basically I was thinking of the word "global" backwards (coming from C# or C++) Declaring global inside of each function instead of declaring global at the very top was what I was doing wrong New functions: function createMatrix($name) { global $matrixa, $matrixb; echo "<h2>" . $name . "</h2>\n"; function loadArrays($name1,$name2) { global $matrixa, $matrixb; Works like a charm!

Ben Ashton · Accepted Answer · 2012-03-16 19:56:28Z

1

In order to use variables generated inside a function, you have to define it as a global variable.

global $variable; $variable=1;

inside your second function you must also tell that $variable is global. Function's variables are otherwise treated local only, and are used specifically for the function itself.

answered Mar 16, 2012 at 19:56

Ben Ashton

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Peter · Accepted Answer · 2012-03-16 20:04:43Z

0

You defined the function as loadArrays() instead of loadMatrix().

answered Mar 16, 2012 at 20:04

Peter

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