Objective-c上的指针 [英] Pointers on Objective-c

问题描述

根据我的理解(如果我错了，请纠正我):

From what I understand (and please correct me if I'm wrong):

int x, count = 10;
int *hello;
hello = &count;
x = *hello;

此处，变量x和count声明为整数类型.此外，变量count被赋值为10.

Here the variables x and count are declared to be of type integer. Additionally, the variable count is assigned the value of 10.

hello是一个指向整数的指针.您好然后分配计数的地址. 为了访问count的值，hello必须在其前面带有一个星号，即* hello.

hello is a pointer to type integer. hello is then assigned the address of count. In order to access the value of count, hello must have an asterisk in front of it, ie, *hello.

因此，为x分配了计数值(在本例中为10)的值.

So, x is assigned the value of whatever is in count and in this case, 10.

但是...

Fraction *myFraction = [[Fraction alloc] init];
[myFraction someMethod];

在这里，如果我理解正确，myFraction是指向Fraction类实例的指针.

Here, if I understand correctly, myFraction is a pointer to an instance of Fraction class.

myFraction指向(或为其分配地址)已分配内存并初始化的对象.

myFraction is pointing to (or rather assigned the address of) an object which has been assigned memory and initialised.

当然，为了访问myFraction指向的对象，我应该写:

Surely, in order to access the object that myFraction points to, I ought to write:

 [*myFraction someMethod];

鉴于x访问count值的方式(肯定是为了访问对象)，应该这样写而不是:

Given the way in which x accessed the value of count, surely in order to access the object, one ought to write this and not:

[myFraction someMethod]; 

此外，如果我有

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSString *str = @"Programming can be a headache";
NSLog (@"%@\n", str);

为什么将str视为上面的对象?还是str是一个对象，在这种情况下，为什么要使其指向NSString类的实例?当然，我应该能够将一个对象分配给str?

Why is str being treated as an object above? Or is str an object and in which case, why would I want to make it point to an instance of NSString class? Surely, I ought to be able to just assign an object to str?

推荐答案

目标c中所有对象的使用都是通过对象引用完成的，例如指针.

All the usage of objects in objective c is done through object references, e.g. pointers.

• 使用Objective C语法，您可以在不取消引用对象的情况下对其进行处理，这与C/C ++有所不同.
• str是类型NSString的对象引用(如myFraction)，@"Programming can be a headache"也是类型NSString的对象引用，因此您可以将其分配给str.

• The Objective C syntax lets you treat objects without dereferencing them, this is different than C / C++ for that matter.
• str is an object reference of type NSString (as myFraction) and @"Programming can be a headache" is an object reference of type NSString as well, so you can assign it to str.

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