如何增加一个指针地址和指针的值？ [英] How to increment a pointer address and pointer's value?

问题描述

让我们假定，

int *p;
int a = 100;
p = &a;

什么将以下code，实际上又是如何？

What will the following code will do actually and how?

p++;
++p;
++*p;
++(*p);
++*(p);
*p++;
(*p)++;
*(p)++;
*++p;
*(++p);

我知道，这是一种凌乱的编码方面，但我想知道我们什么时候code这样会有什么实际发生。

I know, this is kind of messy in terms of coding, but I want to know what will actually happen when we code like this.

请注意：让我们假设 A = 5120300 的地址，它存储在指针 P 地址是 3560200 。现在，将 P和价值;一个每个语句执行后？

Note : Lets assume that the address of a=5120300, it is stored in pointer p whose address is 3560200. Now, what will be the value of p & a after the execution of each statement?

推荐答案

首先，*运营商需要precedence了++运算符，和（）的经营者借此precedence胜于一切。编辑（事情比这更复杂，见底编辑）

First, the * operator takes precedence over the ++ operator, and the () operators take precedence over everything else. EDIT(things are more complicated than that, see bottom edit)

二，数++运算符是一样的号码++运算符，如果你不将其分配给什么。所不同的是++返回数号码，然后递增第一号和++数目的增量，然后返回它。

Second, the ++number operator is the same as the number++ operator if you're not assigning them to anything. The difference is number++ returns number and then increments number, and ++number increments first and then returns it.

三，通过增加指针的值，你的sizeof的递增它的内容，那就是你递增它，就好像你在一个数组迭代。

Third, by increasing the value of a pointer, you're incrementing it by the sizeof its contents, that is you're incrementing it as if you were iterating in an array.

所以，总括起来：

ptr++;    // Pointer moves to the next int position (as if it was an array)
++ptr;    // Pointer moves to the next int position (as if it was an array)
++*ptr;   // The value of ptr is incremented
++(*ptr); // The value of ptr is incremented
++*(ptr); // The value of ptr is incremented
*ptr++;   // Pointer moves to the next int position (as if it was an array). But returns the old content
(*ptr)++; // The value of ptr is incremented
*(ptr)++; // Pointer moves to the next int position (as if it was an array). But returns the old content
*++ptr;   // Pointer moves to the next int position, and then get's accessed, with your code, segfault
*(++ptr); // Pointer moves to the next int position, and then get's accessed, with your code, segfault

由于有很多在这里的情况下，我可能已经取得了一些错误，请纠正我，如果我错了。

As there are a lot of cases in here, I might have made some mistake, please correct me if I'm wrong.

编辑：

所以，我错了，precedence有一点比我写的更复杂，查看这里：
HTTP：//en.cp$p$pference.com / W / CPP /语言/ operator_ precedence

So I was wrong, the precedence is a little more complicated than what I wrote, view it here: http://en.cppreference.com/w/cpp/language/operator_precedence

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