问题
I am working in c++ under ubuntu. I have the following example: [car.h]
#ifndef VEHICLES_CAR_H
#define VEHICLES_CAR_H
// A very simple car class
class Car {
public:
Car();
void shift(int gear);
bool accelerate();
void brake();
int getCurrentSpeed();
int getCurrentGear();
public:
int maxGear;
int currentGear;
int speed;
};
#endif /* VEHICLES_CAR_H *
/ [car.cc]
#include "car.hpp"
#include "car2.hpp"
#include "car2.cc"
#include "car3.h"
#include "car3.cc"
#include <stdio.h>
#include <iostream>
using namespace std;
Car::Car() {
}
void Car::shift(int gear) {
if (gear < 1 || gear > maxGear) {
return;
}
currentGear = gear;
}
bool Car::accelerate() {
speed = 10;
if (speed == 10) return true;
else return false;
}
void Car::brake() {
speed -= (5 *5);
}
int Car::getCurrentSpeed() {
Hello h; //this is in another class...it's working ok
h.say_hello();
speed=5;
return speed;
}
int Car::getCurrentGear() {
return currentGear;
}
[vehicles.cc]
#include "php_vehicles.h"
#include "car.hpp"
zend_object_handlers car_object_handlers;
struct car_object {
zend_object std;
Car *car;
};
zend_class_entry *car_ce;
void car_free_storage(void *object TSRMLS_DC)
{
car_object *obj = (car_object *)object;
delete obj->car;
zend_hash_destroy(obj->std.properties);
FREE_HASHTABLE(obj->std.properties);
efree(obj);
}
zend_object_value car_create_handler(zend_class_entry *type TSRMLS_DC)
{
zval *tmp;
zend_object_value retval;
car_object *obj = (car_object *)emalloc(sizeof(car_object));
memset(obj, 0, sizeof(car_object));
obj->std.ce = type;
ALLOC_HASHTABLE(obj->std.properties);
zend_hash_init(obj->std.properties, 0, NULL, ZVAL_PTR_DTOR, 0);
zend_hash_copy(obj->std.properties, &type->default_properties,
(copy_ctor_func_t)zval_add_ref, (void *)&tmp, sizeof(zval *));
retval.handle = zend_objects_store_put(obj, NULL,
car_free_storage, NULL TSRMLS_CC);
retval.handlers = &car_object_handlers;
return retval;
}
PHP_METHOD(Car, __construct)
{
long maxGear;
Car *car = NULL;
zval *object = getThis();
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "", NULL) == FAILURE) {
RETURN_NULL();
}
car = new Car();
car_object *obj = (car_object *)zend_object_store_get_object(object TSRMLS_CC);
obj->car = car;
}
PHP_METHOD(Car, shift)
{
}
PHP_METHOD(Car, accelerate)
{
Car *car;
car_object *obj = (car_object *)zend_object_store_get_object(
getThis() TSRMLS_CC);
car = obj->car;
if (car != NULL) {
RETURN_BOOL( car->accelerate());
RETURN_LONG(car->speed);
}
}
PHP_METHOD(Car, brake)
{
}
PHP_METHOD(Car, getCurrentSpeed)
{
Car *car;
car_object *obj = (car_object *)zend_object_store_get_object(
getThis() TSRMLS_CC);
car = obj->car;
if (car != NULL) {
RETURN_LONG(car->getCurrentSpeed());
}
RETURN_NULL();
}
PHP_METHOD(Car, getCurrentGear)
{
}
function_entry car_methods[] = {
PHP_ME(Car, __construct, NULL, ZEND_ACC_PUBLIC | ZEND_ACC_CTOR)
PHP_ME(Car, shift, NULL, ZEND_ACC_PUBLIC)
PHP_ME(Car, accelerate, NULL, ZEND_ACC_PUBLIC)
PHP_ME(Car, brake, NULL, ZEND_ACC_PUBLIC)
PHP_ME(Car, getCurrentSpeed, NULL, ZEND_ACC_PUBLIC)
PHP_ME(Car, getCurrentGear, NULL, ZEND_ACC_PUBLIC)
{NULL, NULL, NULL}
};
PHP_MINIT_FUNCTION(vehicles)
{
zend_class_entry ce;
INIT_CLASS_ENTRY(ce, "Car", car_methods);
car_ce = zend_register_internal_class(&ce TSRMLS_CC);
car_ce->create_object = car_create_handler;
memcpy(&car_object_handlers,
zend_get_std_object_handlers(), sizeof(zend_object_handlers));
car_object_handlers.clone_obj = NULL;
return SUCCESS;
}
zend_module_entry vehicles_module_entry = {
#if ZEND_MODULE_API_NO >= 20010901
STANDARD_MODULE_HEADER,
#endif
PHP_VEHICLES_EXTNAME,
NULL, /* Functions */
PHP_MINIT(vehicles), /* MINIT */
NULL, /* MSHUTDOWN */
NULL, /* RINIT */
NULL, /* RSHUTDOWN */
NULL, /* MINFO */
#if ZEND_MODULE_API_NO >= 20010901
PHP_VEHICLES_EXTVER,
#endif
STANDARD_MODULE_PROPERTIES
};
#ifdef COMPILE_DL_VEHICLES
extern "C" {
ZEND_GET_MODULE(vehicles)
}
#endif
[php_vehicles.h]
#ifndef PHP_VEHICLES_H
#define PHP_VEHICLES_H
#define PHP_VEHICLES_EXTNAME "vehicles"
#define PHP_VEHICLES_EXTVER "0.1"
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef __cplusplus
extern "C" {
#endif
#ifdef ZTS
#include "TSRM.h"
#endif
#ifdef __cplusplus
}
#endif
#ifdef __cplusplus
extern "C" {
#endif
#include "php.h"
#ifdef __cplusplus
}
#endif
extern zend_module_entry vehicles_module_entry;
#define phpext_vehicles_ptr &vehicles_module_entry;
#endif /* PHP_VEHICLES_H */
[config.m4]
PHP_ARG_ENABLE(vehicles,
[Whether to enable the "vehicles" extension],
[ --enable-vehicles Enable "vehicles" extension support])
if test $PHP_VEHICLES != "no"; then
PHP_REQUIRE_CXX()
PHP_SUBST(VEHICLES_SHARED_LIBADD)
PHP_ADD_LIBRARY(stdc++, 1, VEHICLES_SHARED_LIBADD)
PHP_NEW_EXTENSION(vehicles, vehicles.cc car.cc, $ext_shared)
fi
[test.php]
<html>
<head>
<title>MY FIRST PHP EXTENSION</title>
</head>
<body>
<?php
$car = new Car();
echo "FIRST RESULT: ".$car->getCurrentSpeed()." "; // prints '0'
//echo "CAR IS: ".$car->accelerate();
if ($car->accelerate() == True) { echo "IT IS TRUE AND SPEED IS: ". $car->$speed;}
//echo "SECOND RESULT: ". $car->getCurrentSpeed()." "; // prints '5'
?>
</body>
</html>
I have the following error at line $car->$speed: Undefined variable: speed in /home/test.php on line 13
PHP Fatal error: Cannot access empty property
WHY? How to solve this? thx ! appreciate
回答1:
Change $car->$speed to $car->getCurrentSpeed():
if ($car->accelerate() == True) { echo "IT IS TRUE AND SPEED IS: ". $car->getCurrentSpeed();}
回答2:
Calling $car->$speed property you should firs define $speed variable.
$speed = 'speed'; // You should define this in PHP code before calling $car->$speed
Calling $car->$speed assumes that you call $car->speed because $speed defined as 'speed'.
It's PHP part of the code.
Or you can simply call $car->speed if you need to access the 'speed' property of $car object
来源：https://stackoverflow.com/questions/7398259/how-to-access-a-variable-from-a-class-using-php-extension