Optional long and string:

long  opt_l = 0;
char *opt_str = NULL;
long  opt_str_len = 0;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC,
    "|ls", &opt_l, &opt_str, &opt_str_len) == FAILURE) {

Get the first two parameters as resource and optional boolean:

zval *resource;
zend_bool b = FALSE;
if (zend_parse_parameters(2 TSRMLS_CC, "r|b", &resource, &b) == FAILURE) {

Get a long or a string:

long  number;
char *str;
int   str_len;

if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC,
    "l", &number) == SUCCESS) {
	/ Do something with the number /
} else if (zend_parse_parameters_ex(ZEND_PARSE_PARAMS_QUIET, ZEND_NUM_ARGS() TSRMLS_CC,
    "s", &str, &str_len) == SUCCESS) {
	/ Do something with the string /
} else {
	/ Output error /
}