PHP file reading and writing technology analysis

PHP file reading and writing technology analysis

In PHP development, file reading and writing are common operations. Whether reading configuration files, processing log files, or dealing with databases, file reading and writing are an indispensable part. This article will introduce the file reading and writing technology in PHP in detail and give corresponding code examples.

1. File reading

1. fopen function

PHP provides the fopen function to open a file and return a file pointer. You can read and write files through the open file pointer.

Function prototype:
resource fopen ( string $filename , string $mode [, bool $use_include_path = FALSE [, resource $context ]] )

Parameter description:

• filename: The name of the file to be opened, which can be a relative path or an absolute path.
• mode: The mode for opening the file. Commonly used ones are 'r' (read-only mode), 'w' (write-only mode) and 'a' (append mode).
• use_include_path: Optional parameter, if set to TRUE, the file will be found in the PHP include path.
• context: Optional parameter, you can specify one or a set of PHP options for the stream.

Code example:

$file = fopen("sample.txt", "r");
if ($file) {
  while (($line = fgets($file)) !== false) {
    echo $line;
  }
  fclose($file);
} else {
  echo "文件打开失败！";
}

2. file_get_contents function

If you just need to load the entire file contents into a string variable, you can Use the file_get_contents function.

Function prototype:
string file_get_contents ( string $filename [, bool $use_include_path = FALSE [, resource $context [, int $offset = -1 [, int $maxlen = NULL ]]]] )

Parameter description:

• filename: The name of the file to be read.
• use_include_path: Optional parameter, if set to TRUE, the file will be found in the PHP include path.
• context: Optional parameter, you can specify one or a set of PHP options for the stream.
• offset: Optional parameter, read the offset of the starting position of the file.
• maxlen: Optional parameter, maximum length to read.

Code example:

$fileContent = file_get_contents("sample.txt");
echo $fileContent;

2. File writing

1. fwrite function

PHP uses the fwrite function to implement Write content into the file. You do this by specifying the file pointer and the content to be written.

Function prototype:
int fwrite ( resource $handle , string $string [, int $length ] )

Parameter description:

• handle: required The file pointer to write to.
• string: Content to be written.
• length: Optional parameter, the maximum length to write. If not specified, the entire string is written.

Code example:

$file = fopen("sample.txt", "w");
if ($file) {
  $content = "Hello, world!";
  fwrite($file, $content);
  fclose($file);
} else {
  echo "文件打开失败！";
}

2. file_put_contents function

If you only need to overwrite or append the entire file content, you can use the file_put_contents function .

Function prototype:
int file_put_contents ( string $filename , mixed $data [, int $flags = 0 [, resource $context ]] )

Parameter description:

• filename: The file name to be written.
• data: The data to be written. Can be a string or an array.
• flags: Optional parameter, writing method, which can be FILE_USE_INCLUDE_PATH, FILE_APPEND, etc.
• context: Optional parameter, you can specify one or a set of PHP options for the stream.

Code examples:

$content = "Hello, world!";
file_put_contents("sample.txt", $content);

This article introduces the technology of reading and writing PHP files and gives corresponding code examples. Whether it is opening a file pointer to read line by line or loading the entire file content into a string variable, it can be easily achieved through the corresponding PHP functions. File writing can be done using the fwrite function or the file_put_contents function. Using these technologies, you can flexibly handle file reading and writing, and develop PHP more efficiently.

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