Bilingual formats is the set of PHP scripts to convert two aligned source texts into one TXT, FB2 or EPUB file with alternating paragraphs. Keep in mind that source texts are not just plain texts but have simple but rather useful specification. The code has been developed and tested with PHP 7.3.33.

This is the very code Bilinguator uses to generate bilingual books — the powerful tool to study languages.

Three scripts are available in the scripts folder:

• save_bilingual_txt.php contains saveBilingualTxt function;
• save_bilingual_fb2.php contains saveBilingualFb2 function;
• save_bilingual_epub.php contains saveBilingualEpub function.

To start using a function from the list, download and plug in the corresponding script into your PHP code with the require or require_once function.

saveBilingualTxt function reads two source files and creates bilingual TXT file with alternating paragraphs.

saveBilingualTxt (
    string $fileAddress1,
    string $fileAddress2,
    string $outputFileAddress = './bilingual.txt'
)

$fileAddress1, $fileAddress2 — paths to the source file 1 and 2 respectively to read.

$outputFileAddress — path to the file where to write the bilingual TXT file. If not specified, the output file will be saved in the working directory named as bilingual.txt.

saveBilingualFb2 function reads two source files and creates bilingual FB2 file with alternating paragraphs.

saveBilingualFb2 (
    string $fileAddress1,
    string $fileAddress2,
    string $outputFileAddress = './bilingual.fb2',
    string $coverAddress = '',
    string $picsFolder = '',
    string $srcLang = '',
    string $lang = '',
    string $id = ''
)

$fileAddress1, $fileAddress2 — paths to the source file 1 and 2 respectively to read.

$outputFileAddress — path to the file where to write the bilingual FB2 file. If not specified, the output file will be saved in the working directory named as bilingual.fb2.

$coverAddress — path to the cover in the PNG format. If not specified, no cover will be added to the book.

$picsFolder — folder in which book illustrations in the PNG format are located. If not specified, no illustrations will be added to the book.

$srcLang — the language code for <src-lang></src-lang> tags in the FB2 books. See the specification for the FB2 format. If not specified, no source language will be added to these tags. Use ISO 639 language codes as prescribed for FB2 format. We recommend to use your first language as the source language.

$lang — the same as for $srcLang but the <lang></lang> tags are filled. We recommend to use your second language for these tags.

$id — unique ID of your book for the <id></id> tags. See the specification for the FB2 format for more information. If not specified, no ID will be added to these tags.

saveBilingualEpub function reads two source files and creates bilingual EPUB file with alternating paragraphs.

saveBilingualEpub (
    $fileAddress1,
    $fileAddress2,
    $outputFileAddress = './bilingual.epub',
    $coverAddress = '',
    $picsFolder = '',
    $lang1 = '',
    $lang2 = '',
    $id = ''
)

$fileAddress1, $fileAddress2 — paths to the source file 1 and 2 respectively to read.

$outputFileAddress — path to the file where to write the bilingual EPUB file. If not specified, the output file will be saved in the working directory named as bilingual.epub.

$coverAddress — path to the cover in the PNG format. If not specified, no cover will be added to the book.

$picsFolder — folder in which book illustrations in the PNG format are located. If not specified, no illustrations will be added to the book.

$lang1 — the language code for the lang attribute in the tags with the corresponding language. If not specified, the lang attributes will be left empty. For more information see the EPUB specification.

$lang2 — the same as for $lang1.

$id — unique ID of your book.

Table below provides the information on how the tags are processed while creating TXT, FB2 and EPUB bilingual files.

See aligned texts specification in the Aligned Texts repository.

In the tests folder you can find the tests.php script with the examples of how to use the Bilingual formats scripts. Three source texts are provided in the folder. First two are the aligned versions of “Le petit prince” in French (le_petit_prince_fr.txt) and German (le_petit_prince_de.txt). The German version contains the title rest on the second line. 47 <imgℕ> tags are in each of the files and 47 PNG images are stored in the tests/img folder. The third source file is the shortened version of the German translation (le_petit_prince_de.short.txt). When the two source files have different counts of articles, the article of the longest one are alternating with empty lines and no error occurs.

The French-German version of “Le petit prince” and many other books are available on our website: bilinguator.com.