2-Create and modify file content

file_put_contentsWrite files

Let’s first learn the first way to write files:

int file_put_contents (string $file Path, string $write data])

Function: Write a string to the specified file. If the file does not exist, create the file. What is returned is the length of written bytes

<?php
    $data = "我是一个兵，来自老百姓";
     $numbytes = file_put_contents('binggege.txt', $data);
     if($numbytes){
 
        echo '写入成功，我们读取看看结果试试：';
 
        echo file_get_contents('binggege.txt');
 
    }else{
        echo '写入失败或者没有权限，注意检查';
    }
?>

We found that writing files is quite simple. According to the format of this function, specify the file and write the string data.

fwrite cooperates with fopen to perform writing operations

int fwrite (resource $file resource variable, string $written string[, int Length])

Note: The alias function of fwrite is fputs

We tried r mode in the last class, and it was only used when reading. Next, we use fwrite plus fopen. w, write mode to write files.

Let’s take a look at the features:

Open in writing mode, point the file pointer to the file header and cut the file size to zero. If the file does not exist then attempts to create it.

Note: In the following experiment, you can try to create a new test.txt file and write content into it. Then, you can try to delete test.txt. See what tips there are.

<?php
    $filename = 'test.txt';
    $fp= fopen($filename, "w");
    $len = fwrite($fp, '我是一只来自南方的狼，一直在寻找心中的花姑娘');
    fclose($fp);
    print $len .'字节被写入了\n";
?>

Summary:
1. Regardless of whether there is a new file, the file will be opened and rewritten
2. The original file content will be overwritten
3. If the file does not exist, it will be created

Let’s compare the differences between the following modes:

## Let’s prove it through experiments:

<?php
    $filename = 'test.txt';
    $fp= fopen($filename, "r+");
    $len = fwrite($fp, '我是一只来自南方的狼，一直在寻找心中的花姑娘');
    fclose($fp);
    print $len .'字节被写入了\n';
?>

You can remove the + sign after r during the experiment.

Through experiments, we have indeed found that using r mode, data can be written when the file is saved. If only r is used, the writing is unsuccessful.

The difference between a mode and w mode

The same code is below, we change it to a mode.

<?php
    $filename = 'test.txt';
    $fp= fopen($filename, "a");
    $len = fwrite($fp,'读大学迷茫了，PHP学院PHP给你希望');
    echo  $len .'字节被写入了\n';
?>

Open the web page and execute this code, you will find: every time you refresh, there will be an extra section in the file

: If you are confused in college, PHP gives you hope.

Summarize:

Note: a+ is an enhanced additional function. It can also be used when it can be read.

The difference between x mode and w mode

Let’s try this code again and change it to x mode:

<?php
    $filename = 'test.txt';
    $fp= fopen($filename, "x");
    $len = fwrite($fp,'读大学迷茫了，PHP学院PHP给你希望');
    echo  $len .'字节被写入了\n';
?>

We will find:

1 . When the file exists, an error will be reported

2. If you change $filename to another file name, it will be fine. However, when refreshing again, an error was reported

3. x+ is an enhanced x mode. Can also be used when reading.

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