Replacing a substring with values from an array in PHP

Question

I am trying to write a JSON file using arrays. Originally, the file was used to create a colorbook.js file on the server and then a manual find and replace to handjam all the values into it. This is the code:

<?php
$colorsperpage = 48; // format is 6 columns by 8 rows
$letters = array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K');
$hexValues = array('ECECEC', 'D9D9D9', 'C7C7C7', 'B4B4B4', 'A2A2A2');

$txt = "var color = {\r\n";

for ($i = 0 ; $i < count($letters) ; $i++){
    $pagenum = $i + 1;
    for ( $j = 1; $j <= $colorsperpage; $j++ ){
        if ($j < 10){
            if ($j == $colorsperpage){
                $txt .= "\t\"" . $letters[$i] . $pagenum . "-" . "0" . $j . "\"  :  \"rgba(255,255,255,1)\"\r\n";
            } else {
                $txt .= "\t\"" . $letters[$i] . $pagenum . "-" . "0" . $j . "\"  :  \"rgba(255,255,255,1)\",\r\n";
            }
        } else {
            if ($j == $colorsperpage){
                $txt .= "\t\"" . $letters[$i] . $pagenum . "-" . $j . "\"  :  \"rgba(255,255,255,1)\"\r\n";
            } else {
                $txt .= "\t\"" . $letters[$i] . $pagenum . "-" . $j . "\"  :  \"rgba(255,255,255,1)\",\r\n";
            }

        }
    }
};


$txt .= "};";

foreach ($hexValues as $hex){
    $txt = preg_replace('/rgba(255,255,255,1)/', $hex, $txt, 1);
}
$jsonFile = fopen('colorbook.js', 'w') or die('Unable to open file!');
fwrite($jsonFile, $txt);
fclose($jsonFile);
?>

The original script did write the file correctly(if you remove the foreach loop). I assumed that running preg_replace would go through that string and one at a time replace the hex values. Note that the original array is 528 items; I shortened it for the sake of posting here. One for each of the RGBA entries. Could someone let me know what I'm doing wrong? Thanks.

Unclear what you are trying to do. Except that you are trying to manually create a json string. That is usually not recommended — Andreas
– Andreas, Commented May 9, 2019 at 16:05
Parentheses have special meaning in regular expressions. It looks like you just want to replace a fixed string, not a pattern, so you should use str_replace(). — Barmar
– Barmar, Commented May 9, 2019 at 16:21
@Andreas Yes, it is a lot of data to create a JSON file by hand so I wanted to use a script to do it. Barmar I will try that. Thanks — DavidG
– DavidG, Commented May 12, 2019 at 0:56
@Barmar that did work but it only uses the first value in the array. I wanted each replace to be the next value in the array. I'm not sure how to do that. Can you help me? — DavidG
– DavidG, Commented May 12, 2019 at 1:01

Barmar · Accepted Answer · 2019-05-13 20:59:37Z

1

Don't create JSON by hand. Build the array in a loop, and use json_encode() on the final result. You can get the hex codes from the array during the loop, rather than doing hundreds of string replacements afterward.

And to format the array keys, you can use sprintf() to concatenate all the pieces and give a leading zero to $j.

<?php
$result = [];
$color_index = 0;
foreach ($letters as $i => $letter) {
    $pagenum = $i + 1;
    for ($j = 1; $j <= $colorsperpage; $j++) {
        $key = sprintf("%s%d-%02d", $letter, $pagenum, $j);
        $colorcode = $hexValues[$color_index++];
        $result[$key] = $colorcode;
    }
}
file_put_contents("colorbook.js", "var color = " . json_encode($result));

edited May 13, 2019 at 20:59

answered May 12, 2019 at 2:14

Barmar

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2 Comments

DavidG Over a year ago

Thanks. It worked I modified it to save the JSON into a variable called color by making it: file_put_contents("colorbook.js", "var color = " . json_encode($result));

DavidG Over a year ago

No, you did a great job! Thanks for your help!

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