Constants for common file functions

The following constant is the most commonly used. Is a constant that is the delimiter of the file directory.

Let’s take a look at the format:

The path format of windows is d:\xxx\xxx Note: Windows supports d:/xxx/xxx
The path format of Linux is /home/xxx/xxx Note: If \home\xxx\xxx is wrong on Linux
So when If you enable escaping, etc., if the escape characters \ are used together, d:\xxx\xxx will be the same. When judging, if there are two \, convert it into one \ and replace the \ with / to split the path, so that the paths on Linux or Windows can remain unified.

We will use a constant:
DIRECTORY_SEPARATOR

Let’s write a small example to define the path of the current file:

Since FILE is PHP’s default Constants are defined, so there is no way to change them. If necessary, FILE can also adapt to the operating system.
Then don’t use FILE. You can use custom constants and process FILE, as follows:

File pointer operation function

rewind (resource handle)

Function: The pointer returns to the beginning

fseek (resource handle, int offset [, int from_where])
Function: The file pointer moves backward Specified characters

In the previous reading, we found that fread reads data of the specified length. Read the content of the specified length. The next time you read it, start from the original position and then read backward.

. The false color of the file is read from A to C

3. The next time you open it, you can start reading from the green arrow of C.

We write a batch of files in the demo.txt file:

abcdeefghijklk

opqrst

uvwxyz

12345678

We can start an experiment .

In the above example, you will find that fseek will move as many bytes as the specified length. And rewind returns to the beginning of the file every time.

How to move to the end? We can count the number of bytes. Move directly to the back during fseek.

Let’s talk about filesize statistics bytes.

filesize detects the size of the file

Other functions for operating files

In fact, there are some other functions for operating files , read the file

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We use an example to use all the above functions.

We write a batch of files in the demo.txt file:

abcdeefghijklk
opqrst
uvwxyz
12345678

fgets opens one line at a time :

With the above code, you will find that each read opens one line at a time. The final read return is false.

Let’s look at the file interception function next:

In the above example, we found that the content can be displayed as long as it is intercepted.