Returns a string produced according to the formatting string 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. This applies to both sprintf() and printf().
Each conversion specification consists of a percent sign (%), followed by one or more of these elements, in order:
An optional padding specifier that says what character will be used for padding the results to the right string size. This may be a space character or a 0 (zero character). The default is to pad with spaces. An alternate padding character can be specified by prefixing it with a single quote ('). See the examples below.
An optional alignment specifier that says if the result should be left-justified or right-justified. The default is right-justified; a - character here will make it left-justified.
An optional number, a width specifier that says how many characters (minimum) this conversion should result in.
An optional precision specifier that says how many decimal digits should be displayed for floating-point numbers. This option has no effect for other types than float. (Another function useful for formatting numbers is number_format().)
A type specifier that says what type the argument data should be treated as. Possible types:
|% - 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 value.|
|d - the argument is treated as an integer, and presented as a (signed) decimal number.|
|u - the argument is treated as an integer, and presented as an unsigned decimal number.|
|f - the argument is treated as a float, and presented as a floating-point number.|
|o - the argument is treated as an integer, and presented as an octal number.|
|s - the argument is treated as and presented as a string.|
|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).|
As of PHP version 4.0.6 the format string supports argument numbering/swapping. Here is an example: