PHP Tutorial - PHP vfprintf() Function


The vfprintf() function writes a formatted string to a specified output stream (file or database).

Unlike fprintf(), the arguments in vfprintf(), are placed in an array.


PHP vfprintf() Function has the following syntax.



This function takes a variable number of parameters: the first parameter is a format string, followed by zero or other parameters of various types.

The format strings for sprintf() is listed as follows.

%% A literal percent character; no matching parameter is required
%b Parameter is an integer; output it as binary
%c Parameter is an integer; output it as a character with that ASCII value
%d Parameter is a positive integer; output it as decimal
%e Scientific notation using a lowercase (e.g. 1.2e+2)
%E Scientific notation using a uppercase (e.g. 1.2E+2)
%f Parameter is a float; express it as a float
%F Floating-point number (not local settings aware)
%g shorter of %e and %f
%G shorter of %E and %f
%o Parameter is an integer; output it as octal
%s Parameter is a string; output it as a string
%uUnsigned decimal number (equal to or greather than zero)
%x Parameter is an integer; output it as hexadecimal with lowercase letters
%X Parameter is an integer; output it as hexadecimal with uppercase letters

Additional format

Additional format values are placed between the % and the letter (example %.2f):

Additional formatMeaning
+Forces both + and - in front of numbers. By default, only negative numbers are marked
'What to use as padding. Default is space. Must be used together with the width specifier. Example: %'q20s (this uses "q" as padding)
-Left-justifies the variable value
[0-9]Minimum width held of to the variable value
.[0-9]Number of decimal digits or maximum string length

The multiple additional format values must be in the same order as above.


Returns the length of the written string

Example 1

Write some text to a text file named "test.txt":

$number = 1;
$str = "PHP";
$file = fopen("test.txt","w");
echo vfprintf($file,"There are %u million %s developers.",array($number,$str));

Example 2

Write some text to a file:

$num1 = 123;
$num2 = 456;
$file = fopen("test.txt","w");

Example 3

Use of placeholders:

$number = 123;
$file = fopen("test.txt","w");
vfprintf($file,"With 2 decimals: %1\$.2f
\nWith no decimals: %1\$u",array($number));


Using printf() to demonstrate all possible format values:

<?php// ww  w .  j  a v  a 2  s.  c om
$num1 = 123456789;
$num2 = -123456789;
$char = 50; // The ASCII Character 50 is 2

// Note: The format value "%%" returns a percent sign
printf("%%b = %b \n",$num1); // Binary number
printf("%%c = %c \n",$char); // The ASCII Character
printf("%%d = %d \n",$num1); // Signed decimal number
printf("%%d = %d \n",$num2); // Signed decimal number
printf("%%e = %e \n",$num1); // Scientific notation (lowercase)
printf("%%E = %E \n",$num1); // Scientific notation (uppercase)
printf("%%u = %u \n",$num1); // Unsigned decimal number (positive)
printf("%%u = %u \n",$num2); // Unsigned decimal number (negative)
printf("%%f = %f \n",$num1); // Floating-point number (local settings aware)
printf("%%F = %F \n",$num1); // Floating-point number (not local settings aware)
printf("%%g = %g \n",$num1); // Shorter of %e and %f
printf("%%G = %G \n",$num1); // Shorter of %E and %f
printf("%%o = %o \n",$num1); // Octal number
printf("%%s = %s \n",$num1); // String
printf("%%x = %x \n",$num1); // Hexadecimal number (lowercase)
printf("%%X = %X \n",$num1); // Hexadecimal number (uppercase)
printf("%%+d = %+d \n",$num1); // Sign specifier (positive)
printf("%%+d = %+d \n",$num2); // Sign specifier (negative)