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($name) which creates a 5×5 matrix of texts boxes and remembers values
loadMatrix($name) which loads a 5×5 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();

Answer 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;
}