How Can I Download Large Files from URLs in PHP without Memory Exhaustion?

Downloading Large Files from URLs without Memory Issues

Web developers commonly encounter the challenge of downloading large files from remote URLs. While the straightforward approach using file_get_contents() and file_put_contents() may suffice for smaller files, it falls short for those exceeding memory limits. This issue prompted the question: how to download large files incrementally without exhausting memory resources.

Fortunately, PHP offers an elegant solution that addresses this concern. Since version 5.1.0, file_put_contents() has supported writing data in chunks by passing a stream handle as the second argument.

Here's the modified code that leverages this feature:

file_put_contents("Tmpfile.zip", fopen("http://someurl/file.zip", 'r'));

This code operates as follows:

• It opens the remote URL as a stream handle using fopen().
• It then supplies this handle to file_put_contents() as the data parameter.
• As the remote file is downloaded, it is progressively written to the local file, Tmpfile.zip, without overloading memory.

The PHP manual explains that passing a stream handle to file_put_contents() triggers the copying of the remaining buffer from the stream to the target file. This mechanism effectively mirrors the functionality of stream_copy_to_stream().

By employing this technique, developers can effortlessly download large files without encountering memory constraints, ensuring seamless data transfer for even the most voluminous file sizes.

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