Arrow operator in PHP vs C - php

Question

I am a PHP programmer trying to learn more of the theory behind PHP, but having trouble connecting the dots between PHP and C. For example, is the arrow operator exactly the same in PHP and C?
Here's what I came up when I researched it:
In C, -> is just an alias, a->b is the same as (*a).b. The arrow operator is just dereferencing a pointer so you interact with the address variable.
In PHP, -> is a reference. It "references the attributes of an instantiated object" (Unknown). But is that the same thing as C?
Note: Today, I learned what pointers are in C.

Answer 1

In PHP, -> is used to access members of a class. C does not have classes.
The closest thing is a struct.
In PHP
class Animal {
public $color;
public $age;
}
$fido = new Animal;
$fido->color = 'white';
$fido->age = 3;
$kitty = new Animal;
$kitty->color = 'brown';
$kitty->age = 5;
// output
echo 'Fido is ' . $fido->color . "age=". $fido->age . "\n";
echo 'Kitty is ' . $kitty->color . "age=". $kitty->age . "\n";
Output is:
Fido is white age=3
Kitty is brown age=5
You can do something similar in C using structs. It's a bit more involved.
Excuse my C. It's quite rusty
struct Animal {
int age;
char color[50];
};
int size = sizeof(struct Animal);
struct Animal * fido = malloc(size);
struct Animal * kitty = malloc(size);
fido->age = 3;
strcpy(fido->color, "white");
kitty->age = 5;
strcpy(kitty->color, "brown");
printf("Fido is %s age=%d\n", fido->color, fido->age);
printf("Kitty is %s age=%d\n", kitty->color, fido->age);
Unless you really want to get into the underlying details, don't overthink PHP references. What that means is that they don't pass around the actual values when doing function calls etc.

Answer 2

Don’t try too hard to find equivalence between the two languages. Their semantics are simply too different, so this will fail.
That said, the dereference operator -> in PHP was likely chosen to visually resemble the member access operator -> in C, and the semantics are somewhat similar, in that both allow you to access a member of a dereferenced object.
I’m not sure what you mean by “In C, -> is just an alias”: The C language has a concept of “alias”, but it’s completely unrelated with the topic at hand.
Rather, -> is an operator, and the expression a->b is defined to be equivalen to (*a).b, as you said correctly. But unlike you said, the object doesn’t need to be allocated on the heap, it can be anywhere in memory. Consider the following:
struct foo {
int i;
};
int main(void) {
struct foo f = {42};
struct foo *pf = &f;
printf("f.i = %d\n", pf->i);
}
Here, pf->i is equivalent to f.i (or (*pf).i). In no case is i allocated on the heap.

Answer 3

In php arrow -> is used to access function of a class.
class A{
function funA(){
return "Hello World";
}
}
$object1 = new A();
$object1->funA;
Object will be
Hello World
You can also access nested objects by arrow operator in PHP.
We will convert string to object. Here is my string:
{
"id":"123456",
"msg":"Have a Nice Day",
"is_active":false,
"total_count":1
}
IF i encode it to JSON
$obj = json_decode($json, false);
I can easily get object value by -> operator
$obj->msg;
OutPut will be
Have a Nice Day
You can do similar in C by using structs.