The printf() statement is ideal when you want to output a blend of static text and dynamic information stored within one or several variables. It’s ideal for two reasons. First, it neatly separates the static and dynamic data into two distinct sections, allowing for easy maintenance. Second, printf() allows you to wield considerable control over how the dynamic information is rendered to the screen in terms of its type, precision, alignment, and position. Its prototype looks like this:

integer printf(string format [, mixed args])

For example, suppose you wanted to insert a single dynamic integer value into an otherwise static string:

printf("Please Wait %d seconds", 30);

Executing this command produces the following:

Please Wait 30 seconds

In this example, %d is a placeholder known as a type specifier, and the d indicates an integer value will be placed in that position. When the printf() statement executes, the lone argument, 100, will be inserted into the placeholder. Remember that an integer is expected, so if you pass along a number including a decimal value (known as a float), it will be rounded down to the closest integer. If you pass along 30.2 or 30.6, then 30 will be output. Pass along a string value such as “one hundred”, and 0 will be output, although if you pass along 123food, then 123 will be output. Similar logic applies to other type specifiers (see this Table for a list of commonly used specifiers).

Type	Description
%b	Argument considered an integer; presented as a binary number
%c	Argument considered an integer; presented as a character corresponding to that ASCII
%d	Argument considered an integer; presented as a signed decimal number
%f	Argument considered a floating-point number; presented as a floating-point number
%o	Argument considered an integer; presented as an octal number
%s	Argument considered a string; presented as a string
%u	Argument considered an integer; presented as an unsigned decimal number
%x	Argument considered an integer; presented as a lowercase hexadecimal number
%X	Argument considered an integer; presented as an uppercase hexadecimal number