Common functions for reading local files in php (fopen and file_get_contents)_php basics

Below we use .txt files as an example to introduce PHP's function of reading local files. To read files, we can use fopen or file_get_contents to read. File_get_contents is simpler, but fopen requires the cooperation of fread to display the read content.

1. First, let’s introduce the fopen() function

Below we give a code demo that directly opens a local file. We have added the necessary places. Annotated:

Copy code The code is as follows:

//Instance code to directly open a local file //Suppose our local file is a text named xmlas.txt
$filedemo = "xmlas.txt";
$fpdemo = fopen($filedemo,"r" );
if ($fpdemo){
while(!feof($fpdemo)){
//Number of characters read by 1000
$datademo = fread($fpdemo, 1000);                                                                   fclose($fpdemo);

2. Use the file_get_contents() function to output the entire file in a string:

Suppose there is such a sentence in our xmlas.txt text file: Current Movies There is less and less passion. If you want to have all the orgasms, please watch Japanese Love

Action movie!
Then the example code of our file_get_contents() function is as follows:

Copy code The code is as follows:

echo file_get_contents("xmlas .txt");
//The output content at this time is the content in xmlas.txt:
//Today’s movies are becoming less and less passionate. If you want to have all the climax, please watch Japanese love action movies!
?>

3. How to read a local folder instead of a separate file:
Please see the example code below. In the example we will read a folder named xmlas :

Copy code The code is as follows:

$dirdemo = opendir('/xmlas');
while(($filedemo = readdir($dirdemo))!= false){
if ($filedemo!="." && $filedemo!="..") {
$nsdemo = explode('.', $filedemo);
echo $nsdemo[0 ];
} }
}
closedir($dirdemo);
?>

4. We can also use fopen to write files

Copy code The code is as follows:

/**
*Write with fopen File
*@param string $filename
*@param string $contents
*@return boolean
*/

function wirte($filename,&$contents)
{
$fp=fopen($filename,"wb");
if($fp)
{
flock($fp,LOCK_EX);//Only one file can be locked at the same time Human operation
fwrite($fp,$contents);
flock($fp,LOCK_UN);//Save the data to unlock the file and save it
fclose($fp);
return true;
}else
{
return false;
}
}

In this way, I only need to use fopen and fwrite to read and write files.

Note: lOpen the file

Before opening the file, we need to know the path of the file and whether the file exists.

Use the $_SERVER["DOCUMENT_ROOT"] built-in global variable to obtain the relative path of the site. As follows:

Copy code The code is as follows:

$root = $_SERVER[“DOCUMENT_ROOT”];

Using the function file_exists() to detect whether the file exists. As follows:

Copy code The code is as follows:

If(!file_exists("$root/order. txt")){echo 'File does not exist';}

This may be more reasonable and practical.