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>Chapter 32. Accepting Arguments</TD
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>Dealing with a Variable Number of Arguments/Optional Parameters</H1
><P
>&#13;    If your function is meant to accept a variable number of
    arguments, the snippets just described are sometimes suboptimal
    solutions. You have to create a line calling
    <B
CLASS="function"
>zend_get_parameters_ex()</B
> for every possible
    number of arguments, which is often unsatisfying.
   </P
><P
>&#13;    For this case, you can use the
    function <B
CLASS="function"
>zend_get_parameters_array_ex()</B
>, which accepts the
    number of parameters to retrieve and an array in which to store them: 
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><PRE
CLASS="programlisting"
>zval **parameter_array[4];

/* get the number of arguments */
argument_count = ZEND_NUM_ARGS();

/* see if it satisfies our minimal request (2 arguments) */
/* and our maximal acceptance (4 arguments) */
if(argument_count &#60; 2 || argument_count &#62; 5)
    WRONG_PARAM_COUNT;

/* argument count is correct, now retrieve arguments */
if(zend_get_parameters_array_ex(argument_count, parameter_array) != SUCCESS)
    WRONG_PARAM_COUNT;</PRE
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>
    First, the number of arguments is checked to make sure that it's in the accepted range. After that,
    <B
CLASS="function"
>zend_get_parameters_array_ex()</B
> is used to
    fill <TT
CLASS="envar"
>parameter_array</TT
> with valid pointers to the argument
    values.
   </P
><P
>&#13;    A very clever implementation of this can be found in the code
    handling PHP's <A
HREF="function.fsockopen.html"
><B
CLASS="function"
>fsockopen()</B
></A
> located in
    <TT
CLASS="filename"
>ext/standard/fsock.c</TT
>, as shown in 
    <A
HREF="zend.arguments.variable.html#example.fsockopen"
>Example 32-1</A
>. Don't worry if you don't know all the functions used in this
    source yet; we'll get to them shortly.
   </P
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><B
>Example 32-1. PHP's implementation of variable arguments in fsockopen().</B
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><PRE
CLASS="programlisting"
>pval **args[5];
int *sock=emalloc(sizeof(int));
int *sockp;
int arg_count=ARG_COUNT(ht);
int socketd = -1;
unsigned char udp = 0;
struct timeval timeout = { 60, 0 };
unsigned short portno;
unsigned long conv;
char *key = NULL;
FLS_FETCH();

if (arg_count &#62; 5 || arg_count &#60; 2 || zend_get_parameters_array_ex(arg_count,args)==FAILURE) {
    CLOSE_SOCK(1);
    WRONG_PARAM_COUNT;
}

switch(arg_count) {
    case 5:
        convert_to_double_ex(args[4]);
        conv = (unsigned long) (Z_DVAL_P(args[4]) * 1000000.0);
        timeout.tv_sec = conv / 1000000;
        timeout.tv_usec = conv % 1000000;
        /* fall-through */
    case 4:
        if (!PZVAL_IS_REF(*args[3])) {
            php_error(E_WARNING,"error string argument to fsockopen not passed by reference");
        }
        pval_copy_constructor(*args[3]);
        ZVAL_EMPTY_STRING(*args[3]);
        /* fall-through */
    case 3:
        if (!PZVAL_IS_REF(*args[2])) {
            php_error(E_WARNING,"error argument to fsockopen not passed by reference");
            return;
        }
        ZVAL_LONG(*args[2], 0);
        break;
}

convert_to_string_ex(args[0]);
convert_to_long_ex(args[1]);
portno = (unsigned short) Z_LVAL_P(args[1]);

key = emalloc(Z_STRLEN_P(args[0]) + 10);</PRE
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><P
>&#13;    <A
HREF="function.fsockopen.html"
><B
CLASS="function"
>fsockopen()</B
></A
> accepts two, three, four, or five
    parameters. After the obligatory variable declarations, the
    function checks for the correct range of arguments. Then it uses a
    fall-through mechanism in a <TT
CLASS="literal"
>switch()</TT
> statement
    to deal with all arguments. The  <TT
CLASS="literal"
>switch()</TT
>
    statement starts with the maximum number of arguments being passed
    (five). After that, it automatically processes the case of four
    arguments being passed, then three, by omitting the otherwise
    obligatory <TT
CLASS="literal"
>break</TT
> keyword in all stages. After
    having processed the last case, it exits the
    <TT
CLASS="literal"
>switch()</TT
> statement and does the minimal
    argument processing needed if the function is invoked with only
    two arguments.
   </P
><P
>&#13;    This multiple-stage type of processing, similar to a stairway, allows
    convenient processing of a variable number of arguments.
   </P
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