Detailed explanation on how to use php to modify the specified content of txt file?

PHP is a very popular network programming language used for developing web applications, which involves reading, writing and modifying local text files.

In this article, we will discuss how to use PHP to modify the content of a specified text file. The following are a few steps:

Step 1: Open the text file

Use the function fopen() to open a text file in PHP. This function requires two parameters: file name and file access mode. filename is the name of the text file to be opened. File access mode specifies how you want to handle the file. Here, we will use "w" mode, which means read and write. This mode will create a new file or overwrite an existing file. It also allows us to read the contents of the current file.

The following is a sample code:

$filename = "example.txt";
$file = fopen($filename, "w+");
if($file === false){
 die("Unable to open file");
}
//文件打开成功，可以继续下一步骤

Step 2: Read the file content

Use the function fread() to read the content of the open text file . It takes two parameters: the file pointer and the number of bytes to read. We can use a while loop to read the contents of the entire file.

The following is a sample code:

$file = fopen($filename, "r");
if($file === false){
 die("Unable to open file");
}
$contents = '';
while (!feof($file)) {
$contents .= fread($file, 8192); //读取8192个字节，并将它们添加到$contents变量中
}
fclose($file);

Step 3: Modify the specified content

The main method to modify the text file is to use PHP’s string function search And replace the characters you want to modify, the following is the sample code:

$file = file_get_contents('example.txt');
$file = str_replace('old_string', 'new_string', $file);
file_put_contents('example.txt', $file);

In this sample code, we first read the contents of the entire text file, and then we use PHP’s string function str_replace() to search and replacement. 'old_string' refers to the content to be replaced in the current file, and 'new_string' refers to replacing it with the desired content. Finally, we use the function file_put_contents() to rewrite the modified content back to the text file.

Step 4: Close the file

After completing the file modification, remember to close the file. In PHP, use the function fclose() to do this.

The following is the sample code:

$file = fopen($filename, "r+");
if($file === false){
 die("Unable to open file");
}
// 修改文件内容，将"Hello World"替换为"Hello PHP"  
$file_contents = file_get_contents($filename);
$file_contents = str_replace("Hello World", "Hello PHP", $file_contents);
fwrite($file, $file_contents);
fclose($file);

The above is how to use PHP to modify the content of a text file. With this simple code you can easily modify your text files and it will work with any text editor.

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