Introduction to PHP functions—fgets(): Read a line from a file

PHP function introduction—fgets(): Read a line from a file

In PHP, many functions are provided for file reading and writing. Among them, the fgets() function is one of the functions used to read the content line by line from the file. This article will introduce the fgets() function and demonstrate its usage through code examples.

fgets() function is one of the file input functions in PHP, used to read a line of content from a file. Its basic syntax is as follows:

string fgets(resource $handle [, int $length])

Among them, $handle represents the opened file pointer, or it can be a URL or input buffer stream Or other legal file pointer resources. The $length parameter is optional and represents the maximum length of bytes to be read. If the $length parameter is omitted, the entire line is read by default, including the newline character at the end of the line.

The following is an example of using the fgets() function:

// Open the file
$file = fopen("example.txt", "r ");

//Read a line of content
$line = fgets($file);

//Output the read content
echo $line;

//Close the file
fclose($file);
?>

In the above example, a file named example.txt is first opened using the fopen() function , and specify the opening mode as read-only mode ("r"). Then use the fgets() function to read the first line of the file, and finally use echo to output the read content. Finally, the file is closed using the fclose() function.

It should be noted that the fgets() function only reads one line of content at a time. If you want to read multiple lines, you need to call the fgets() function multiple times.

In addition, when reading to the end of the file, the fgets() function will return false. Therefore, you can use a loop to read the contents of the entire file until you reach the end of the file. The following is an example:

// Open file
$file = fopen("example.txt", "r");

// Read Get the file content
while(!feof($file)) {

// 读取一行内容
$line = fgets($file);

// 输出读取的内容
echo $line;

}

// Close the file
fclose($file);
?>

In this example, a while loop is used to read the contents of the entire file. The feof() function is used to determine whether the end of the file has been reached. As long as the end of the file is not reached, the fgets() function will continue to be called to read the next line of content and output the content to the screen.

Through the above examples, we can see how simple and practical the fgets() function is. Whether you are reading a line of a file or the contents of the entire file, you can easily do so with the fgets() function.

In general, the fgets() function is one of the functions in PHP used to read content line by line from a file. Through this function, we can easily read one or more lines of the file and process it accordingly. After mastering the usage of the fgets() function, you can more flexibly operate the file reading task and improve the readability and maintainability of the code.

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