(PHP 4 >= 4.1.0, PHP 5, PHP 7)
vprintf — Output a formatted string
$format
   , array $args
   ) : int
   Display array values as a formatted string according to
   format (which is described in the documentation
   for sprintf()).
  
Operates as printf() but accepts an array of arguments, rather than a variable number of arguments.
format
   The format string is composed of zero or more directives:
   ordinary characters (excluding %) that are
   copied directly to the result and conversion
   specifications, each of which results in fetching its
   own parameter.
  
   A conversion specification follows this prototype:
   %[argnum$][flags][width][.precision]specifier.
  
    An integer followed by a dollar sign $,
    to specify which number argument to treat in the conversion.
   
| Flag | Description | 
|---|---|
| - | Left-justify within the given field width; Right justification is the default | 
| + | Prefix positive numbers with a plus sign +; Default only negative
        are prefixed with a negative sign. | 
|  (space) | Pads the result with spaces. This is the default. | 
| 0 | Only left-pads numbers with zeros.
        With sspecifiers this can
        also right-pad with zeros. | 
| '(char) | Pads the result with the character (char). | 
An integer that says how many characters (minimum) this conversion should result in.
    A period . followed by an integer
    who's meaning depends on the specifier:
    
e, E,
       f and F
       specifiers: this is the number of digits to be printed
       after the decimal point (by default, this is 6).
      
     g and G
       specifiers: this is the maximum number of significant
       digits to be printed.
      
     s specifier: it acts as a cutoff point,
       setting a maximum character limit to the string.
      
     Note: If the period is specified without an explicit value for precision, 0 is assumed.
Note: Attempting to use a position specifier greater than
PHP_INT_MAXwill generate warnings.
| Specifier | Description | 
|---|---|
| % | A literal percent character. No argument is required. | 
| b | The argument is treated as an integer and presented as a binary number. | 
| c | The argument is treated as an integer and presented as the character with that ASCII. | 
| d | The argument is treated as an integer and presented as a (signed) decimal number. | 
| e | The argument is treated as scientific notation (e.g. 1.2e+2). The precision specifier stands for the number of digits after the decimal point since PHP 5.2.1. In earlier versions, it was taken as number of significant digits (one less). | 
| E | Like the especifier but uses
        uppercase letter (e.g. 1.2E+2). | 
| f | The argument is treated as a float and presented as a floating-point number (locale aware). | 
| F | The argument is treated as a float and presented as a floating-point number (non-locale aware). Available as of PHP 5.0.3. | 
| g | General format. Let P equal the precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. Then, if a conversion with style E would have an exponent of X: If P > X ≥ −4, the conversion is with style f and precision P − (X + 1). Otherwise, the conversion is with style e and precision P − 1. | 
| G | Like the gspecifier but usesEandf. | 
| o | The argument is treated as an integer and presented as an octal number. | 
| s | The argument is treated and presented as a string. | 
| u | The argument is treated as an integer and presented as an unsigned decimal number. | 
| x | The argument is treated as an integer and presented as a hexadecimal number (with lowercase letters). | 
| X | The argument is treated as an integer and presented as a hexadecimal number (with uppercase letters). | 
    The c type specifier ignores padding and width
   
Attempting to use a combination of the string and width specifiers with character sets that require more than one byte per character may result in unexpected results
Variables will be co-erced to a suitable type for the specifier:
| Type | Specifiers | 
|---|---|
| string | s | 
| integer | d,u,c,o,x,X,b | 
| double | g,G,e,E,f,F | 
args
Returns the length of the outputted string.
Example #1 vprintf(): zero-padded integers
<?php
vprintf("%04d-%02d-%02d", explode('-', '1988-8-1'));
?>
The above example will output:
1988-08-01