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This article focuses on "how to use php to read the last few lines of data in the file code", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to use php to read the last few lines of data in a file.

In php, you can use the file () and array_slice () functions to read the last few lines of data in the file and implement the code "array_slice (file ($file,FILE_IGNORE_NEW_LINES),-lines)".

Operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Php reads the last few lines of data in the file

Realize the idea:

With the help of the file () function, the whole file data is stored in an array, and each row of data corresponds to an array element.

You can get the last few elements of the array with the help of the array_slice () function.

Implementation code:

Output result:

Description:

The file () function stores the contents of the file in an array by line (including newline characters). This array is returned if successful, and FALSE is returned if failed. The syntax format of the file () function is as follows:

File ($filename,$flags,$context)

This function takes one required parameter, $filename (the file to be read), and two omitted parameters $flags and $context (the environment of the file handle).

However, the $flags parameter is generally set, which can be one or more of the following constants:

FILE_USE_INCLUDE_PATH: look for files in include_path (in php.ini). The default is FALSE;. If you want to, set the parameter value to'1'.

FILE_IGNORE_NEW_LINES: do not add newline characters at the end of each element of the array

FILE_SKIP_EMPTY_LINES: skip blank lines.

The array_slice () function is a function provided by PHP to intercept an array and extract a fragment from the array. The syntax is as follows:

Array array_slice (array $arr, int $start [, int $length = NULL [, bool $preserve_keys = false]])

Parameter description:

Arr represents the array to be intercepted.

Start indicates where to start the intercept (subscript):

If start is positive, it is intercepted from the back of the go.

If the start is negative, it is intercepted from back to front, starting at the distance from the end of the arr-start. For example,-2 means starting with the penultimate element of the array.

Length is an optional parameter that indicates the intercept length:

If length is positive, it indicates the number of elements intercepted

If length is negative, the intercepted fragment will terminate at the position of length at the end of the distance array

If omitted, it starts at the start position and goes all the way to the end of the array.

Preserve_keys is an optional parameter, which specifies whether to keep the original key name. The default is false, that is, it is not retained. If set to true, the original key name will be retained.

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