PHP String fprintf() Function

---

---

The PHP String fprintf() function is used to write a prepared string to a specified output stream (e.g. a file or database).

At percent (%) signs, the parameters arg1, arg2, and ++ will be appended to the main string. "Step-by-step" is how this function operates. The first % sign is where arg1 is entered, followed by the second % sign and so forth.

Syntax

Below is the syntax of the PHP String fprintf() function −

int fprintf(resource $stream, string $format, mixed ...$values)

Parameters

Below are the parameters of the fprintf() function −

• $stream − It is a valid resource for a file pointer (created using fopen() or a similar method). This is where the formatted string will be written.

• $format − It is a string that defines the format for the values. Like printf(), it makes use of placeholders like %s, %d, etc.

• $values − It is used to indicate one or more values to be formatted and added to the $format string.

Return Value

The fprintf() function returns the length of the string written.

PHP Version

First introduced in core PHP 5, the fprintf() function continues to function easily in PHP 7, and PHP 8.

Example 1

First we will show you the basic example of the PHP String fprintf() function to write a string in the given file path.

<?php
// Open the file for writing
$file = fopen("/PHP/PhpProjects/filetext.txt", "w");

if ($file) {
    $name = "Amit";
    $age = 25;

    // Write formatted data to the file
    fprintf($file, "Name: %s, Age: %d\n", $name, $age);

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

Output

Here is the outcome of the following code −

Name: Amit, Age: 25

Example 2

In the below PHP code we will try to use the fprintf() function and data is appended to an existing file. The fopen()'s a mode allows data to be inserted to the end of the file without overwriting its contents.

<?php
// Open the file for appending
$file = fopen("/PHP/PhpProjects/filetext.txt", "a");

if ($file) {
    $product = "Laptop";
    $price = 1200;

    // Append formatted text to the file
    fprintf($file, "Product: %s, Price: $%d\n", $product, $price);

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

Output

This will generate the below output −

Product: Laptop, Price: $1200

Example 3

Now the below code writes multiple lines of formatted data to a file with the help of fprintf() function.

<?php
// Open the file for writing
$file = fopen("/PHP/PhpProjects/student.txt", "w");

if ($file) {
    // Write formatted lines for multiple students
    fprintf($file, "Student: %s, Score: %d\n", "Amit", 88);
    fprintf($file, "Student: %s, Score: %d\n", "Chetan", 92);

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

Output

This will create the below output −

Student: Amit, Score: 88
Student: Chetan, Score: 92

Example 4

In the following example, we are using the fprintf() function to write a formatted string with floating point numbers.

<?php
// Open the file for writing
$file = fopen("/PHP/PhpProjects/groceries.txt", "w");

if ($file) {
    $item = "Groceries";
    $cost = 4575;

    // Write formatted text with a floating-point number
    fprintf($file, "Item: %s, Cost: Rs %.2f\n", $item, $cost);

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

Output

Following is the output of the above code −

Item: Groceries, Cost: Rs 4575.00