PHP fscanf() Function

What is PHP fscanf() Function?

If you want to parse (analyze and convert) inputs from an open file into variables based on a specified format, use fscanf() function.

Syntax:

fscanf(file, format, variable1, variable2,…)

Parameters:

The Function has 2 required parameter2 and any number of optional parameters-

file (Required): It specifies a file system pointer resource that usually created with fopen() function.

format (Required): It specifies the pattern to use for formatting the input string. For formatting, the follows the rules that are described in sprint() function, except the followings-

  • Function is not locale-aware.
  • F, g, G and b are not supported.
  • D stands for decimal number.
  • i stands for integer with base detection.
  • n stands for number of characters processed so far.
  • s stops reading at any whitespace character.
  • instead of argnum$ suppresses the assignment of this conversion specification.

variable1, variable2,… (Optional): It specifies one or more variables that holds the parsed values.

Return Values:

The return value depends on whether or not the optional variables are used-

  • When no optional variables are used: The function returns an array containing all the parsed values.
  • When optional variables are used: The function stores the parsed values in those variables and returns those.
    • The function returns NULL if there are more formatting rules in the format parameter than available substrings in the input string.

Practical Usages of fscanf() Function:

Here are some practical usages of fscanf() function-

  1. Converting color codes from Hexadecimal to its equivalent RGB code using %x or %X format specifier-
    <?php
/* Suppose, the following line is written in the file named file.txt-
FF0000
*/
$handle = fopen("file.txt", "r");
list($r, $g, $b) = fscanf($handle, '%2x%2x%2x');
echo "RGB color code of Hexadecimal code \"FF0000\" is: $r, $g, $b";
?>

    Output:

    RGB color code of Hexadecimal code "FF0000" is: 255, 0, 0

  2. Extracting data from log file-
    <?php
/* Suppose, the following line is written in the file named file.txt-
2025-12-29 17:30:05 INFO: User logged in
*/
$handle = fopen("file.txt", "r");
list($year, $month, $day) = fscanf($handle, "%d-%d-%d");
echo "User's logged in date was: " . $month . "/" . $day . "/" . $year;
?>

    Output:

    User's logged in date was: 12/29/2025

  3. Extracting product no. from product code-
    <?php
/* Suppose, the following line is written in the file named file.txt-
CRN/5117
*/
$handle = fopen("file.txt", "r");
fscanf($handle, "CRN/%d", $serial_no);
echo "Serial number of the product code is: " . $serial_no;
?>

    Output:

    Serial number of the product code CRN/5117is: 5117

  4. Parsing from specific delimiter-
    <pre>
<?php
/* Suppose, the following line is written in the file named file.txt-
ID: 1, Name: John 
*/
$handle = fopen("file.txt", "r");
list($id, $name) = fscanf($handle, "ID: %d, Name: %s, Sex: %s");
echo "Person name: ". $name . " and his id is: " . $id;
?>
</pre>

    Output:

    Person name: John and his id is: 1

  5. For parsing a string that has fixed patterns, fscanf() is usually faster than preg_match() function.

PHP Version Support:

PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8

Summary: PHP fscanf() Function

The fscanf() function is a built-in PHP function and part of the PHP’s string functions. Use this function to extract information from structural data that is stored in a file.

Reference:

https://www.php.net/manual/en/function.fscanf.php