Programming PHP

The other type_spec specifying characters are given in Table 14-2.
Table 14-2. Type specification characters
Character Description
l Long
d Double
s String (with possible NUL-bytes) and its length
b Boolean, stored in zend_bool
r Resource (stored in zval)
a Array
o Object (of any type)
O Object (of specific type, specified by class entry)
z The actual zval
The modifiers that can follow each of these are given in Table 14-3.
Table 14-3. Type specification modifiers
Modifier Description
| This indicates that all remaining parameters will be optional. Remember to initialize these yourself if they are
not passed by the user. These functions will not put any default values in the parameters.
/ This indicates that the preceding parameter should be separated from the calling parameter, in case you wish to
modify it locally in the function without modifying the original calling parameter.
! This applies only to zval parameters (a, o, O, r, and z) and indicates that the parameter it follows can be
passed a NULL. If the user does pass a NULL, the resulting container is set to NULL.
A Simple Example
The following code gets a long (all integers in PHP are longs), a string, and an
optional double (all floating-point values in PHP are double-precision):
long l;
char *s;
int s_len;
double d = 0.0;
if (zend_parse_parameters(ZEND_NUM_ARGS( ) TSRMLS_CC, "ls|d", &l, &s, &s_len)
== FAILURE) return;
From a PHP script, this function might be called like this:
$num = 10; $desc = 'This is a test'; $price = 69.95;
add_item($num, $desc); // without the optional third argument
add_item($num, $desc, $price); // with the optional third argument
This results in long l being set to 10, char *s containing the string “This is a Test”, and
s_len being set to 14. For the first call, double d maintains the default 0.0 value that
you set, but in the second call, where the user provides an argument, it is set to 69.95.
336 | Chapter 14: Extending PHP
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