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This article mainly introduces the "large file reading operation in PHP". In the daily operation, I believe that many people have doubts about the large file reading operation in PHP. The editor consulted all kinds of data and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "large file reading operation in PHP". Next, please follow the editor to study!

PHP large file read operation

For simple file reading, we usually use methods such as file_get_contents () to get the contents of the file directly. However, a serious problem with this function is that it loads the file into memory at once, that is, it is limited by memory. Therefore, this method should never be used when loading large files. Let's first look at an example of loading in this way.

/ / ordinary file reads a 2.4G SQL export file

$fileName='. / 2020-02-23.sql'

/ / file_get_contents

$fileInfo = file_get_contents ($fileName)

/ / Fatal error: Allowed memory size of 134217728 bytes exhausted

/ / file

$fileInfo = file ($fileName)

/ / Fatal error: Allowed memory size of 134217728 bytes exhausted

/ / fopen + fread

$fileHandle = fopen ($fileName,'r')

$fileInfo = fread ($fileHandle, filesize ($fileName))

/ / Fatal error: Allowed memory size of 134217728 bytes exhausted

None of the above three file loading and reading methods can load such large files. Of course, you can also modify the relevant configuration in php.ini to make them load successfully, but this is not recommended. After all, memory resources are much more valuable than hard disk resources.

You can read such a large file directly in the following ways:

/ / readfile can only output directly

Echo readfile ($fileName)

/ / fopen + fgetc if single

$fileHandle = fopen ($fileName,'r')

/ / output single characters until end-of-file

While (! feof ($fileHandle)) {

Echo fgetc ($fileHandle)

}

Fclose ($fileHandle)

/ / SplFileObject

$fileObject = new SplFileObject ($fileName,'r')

While (! $fileObject- > eof ()) {

Echo $fileObject- > fgetc ()

}

The first readfile () is printed directly after reading the file, and no other operations can be carried out. It is suitable for directly displaying the contents of large files.

The second fopen () with fgetc () or fgets () is standard for reading such large files. Fopen () gets the file handle, fgetc () reads by character, and fgets () reads by line. For a file like this mysqldump, the line may also be very large, so we can only read it directly by character.

The third is the object-oriented fopen () operation provided by the SPL extension library. It is suggested that if there is a need to read large files in the new development, it is best to use this form of writing. After all, the SPL function library is already the standard function library of PHP, and the object-oriented operation form is more mainstream.

One thing to note about the above three reading methods is that large files should not be saved to variables after reading, but should be directly printed, stored or written to other files. Because reading directly into a variable is the same as reading directly to memory, it is not as convenient to modify the configuration of php.ini and read directly to memory using the top method. Again, memory is left where it is really needed, and for such large files, it is best to perform IO operations on the hard disk.

Test code: https://github.com/zhangyue0503/dev-blog/blob/master/php/202003/source/PHP%E5%A4%A7%E6%96%87%E4%BB%B6%E8%AF%BB%E5%8F%96%E6%93%8D%E4%BD%9C.php

At this point, the study on "large file read operation in PHP" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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