Specifications

Both of these techniques print a string “as is.” You can apply some more sophisticated format-

ting using the functions printf() and sprintf(). These work basically the same way, except

that printf() prints a formatted string to the browser and sprintf() returns a formatted

string.

If you have previously programmed in C, you will find that these functions are the same as the

C versions. If you haven’t, they take getting used to but are useful and powerful.

The prototypes for these functions are

string sprintf (string format [, mixed args...])

int printf (string format [, mixed args...])

The first parameter passed to both these functions is a format string that describes the basic

shape of the output with format codes instead of variables. The other parameters are variables

that will be substituted in to the format string.

For example, using

echo, we used the variables we wanted to print inline, like this:

echo “Total amount of order is $total.”;

To get the same effect with printf(), you would use

printf (“Total amount of order is %s.”, $total);

The %s in the format string is called a conversion specification. This one means “replace with a

string.” In this case, it will be replaced with $total interpreted as a string.

If the value stored in $total was 12.4, both of these approaches will print it as 12.4.

The advantage of printf() is that we can use a more useful conversion specification to specify

that $total is actually a floating point number, and that it should have two decimal places after

the decimal point, as follows:

printf (“Total amount of order is %.2f”, $total);

You can have multiple conversion specifications in the format string. If you have n conversion

specifications, you should have n arguments after the format string. Each conversion specifica-

tion will be replaced by a reformatted argument in the order they are listed. For example

printf (“Total amount of order is %.2f (with shipping %.2f) “,

$total, $total_shipping);

Here, the first conversion specification will use the variable $total, and the second will use

the variable $total_shipping.

Each conversion specification follows the same format, which is

%[‘padding_character][-][width][.precision]type

Using PHP

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