调用未定义的函数xmlwriter_open_memory（），没有OOP

Question

I am writing a school project in PHP but I am not using classes. I need to write the output to XML with wmlwriter_open_memory() and tried things like this:

$xml = xmlwriter_open_memory();

$xml = XMLWriter::xmlwriter_open_memory();

$xml = new XMLWriter();
...

But I get the call to undefined function error, but the curious thing is, I don't get the error when I remotely run in on the school server.

I am using PHP 7.2.15 and Ubuntu 18.04.1 LTS. Any ideas are appreciated.

Answer 1

as @ThW has stated, I didn't have the extension installed, but my IDE recognized that the function exists, so that confused me the most.

I've solved it by installing the php extension like this:

sudo apt-get install php-xml

and made sure that it is installed with this

php -i | grep "xml"

I found these commands here