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NULL pointer and void pointer in c ++NULL Pointer nullptr previously used 0 or NULL to express NULL pointers:The NULL macro of C/C ++ is a macro with many potential bugs. Some databases define it as an integer 0, while others define it as (void *) 0. It's okay in the C era. However, in the C ++ era, this will cause many problems.C ++ 11 uses the nullptr keyword,

---restore content starts---My understanding is that, regardless of the type defined when the pointer is defined, the pointer is essentially a number, and the number of bits is determined by the compiler.For example, my compiler is a 32-bit, then whether it is defined as a char *pc or an int *pi, essentially the PC and PI are a 32-bit number, but due to "char *" and "int *" limit, so pc++ is self-added 8bit

A function always occupies a contiguous area of memory, and the function name is sometimes converted to the first address of the memory area where the function is located, and the array name is very similar. We can assign this first address (or the entry address) of a function to a pointer variable so that the pointer variable points to the memory area where the function is located, and then the function ca

The pointer function generally refers to the function that returns the pointer; #include A function pointer is a pointer to the start address of a function:The first step is to understand the call procedure for a function: #include A function can be invoked with R = (*fun) (5), which means t

1.const int *p Is the so-called "pointer to a constant". Note here that the so-called "pointing constant" is only the "wishful thinking" of the pointer, but an effect of equivalence. In fact, the const int *p=a;a can be both a constant (const int a=10;) and a variable (int a=10;), but p wishful thinking that it refers to a constant, so it does not allow itself to modify the meaning, which creates an effect

1, because the QQ space of the pointer icon so we first into the QQ space to download, such as I entered the QQ space and then click on "Dress Up"-"Dress up The Mall"-"single product"-"decoration"-"mouse" the following figure. 2, here is not a lot of pointer icon Yes, we find a favorite right click icon, and then click on the pop-up menu "Properties" 3, such as the picture in the Pop-up property windo

OneThis "pointer function" and "function pointer" are easy to mistake in learning arm, so today, I want to make it clear at once and find some information, first of all, the definition between them:1, pointer function refers to a function with a pointer, that is, the essence is a function. A function return type is a

OneThis "pointer function" and "function pointer" are easy to mistake in learning arm, so today, I want to make it clear at once and find some information, first of all, the definition between them:1, pointer function refers to a function with a pointer, that is, the essence is a function. A function return type is a

What is a null pointer constant (null pointer constant )? [6.3.2.3-3] An integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant. Here we will tell you: 0, 0L, '\ 0', 3-3, 0*17 (they are all "integer constant expression") and (void *) 0 (tyc: I think (void *) 0 should be regarded as a null

Generally, pointer variables are used to define pointer variables, assign values to pointer variables, and reference pointer variables. The description is as follows: (1) define pointer Variables In the variable definition statement int * P, * P1, * q;, all variables defined

What is a null pointer constant (NULL pointer constant )?[6.3.2.3-3] an integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant.Here we will tell you: 0, 0l, '/0', 3-3, 0*17 (they are all "integer constant expression") and (void *) 0 (tyc: I think (void *) 0 should be regarded as a null

I, When I learned about arm, I found that the "pointer function" and "function pointer" are easy to make mistakes. So today, I want to figure it out and find some information, first, the definitions between them: 1. A pointer function is a function with a pointer. A function returns a

Two-dimensional array: int a [3] [4] = {1, 2, 3, 4}, {5, 6, 7, 8}, {9, 8, 7, 6 }}; pointer array: int * pa [4]; Note: 1. the pointer array is actually an array, but the elements in the array are pointers, in this example, arrays are stored in pa [0], pa [1], pa [2], and pa [3]. 2. assign a value to a two-dimensional array. a single value is required, that is, * pa = a; * (pa + 1) = a [1]; * (pa + 2) = a [2]

First, the structural body pointer1. What is a struct pointer? Pointer to struct-body variablestruct: typedef struct stu{Char name[20];char sex;int age;}student;Student stu1 = {"Zhangsan", ' m ', 23};Student *p = stu1; p is a struct pointer that holds the address of the first member of a struct variable.Student stu2 ={"Lisi", ' m ', 26};*p = STU2;(*p). Sex = ' f

There is such a problem that how to use an integer to save a struct or class and other types of pointers. This requirement exists between different languages. For example, there is a struct: Struct a {char Item1; int item2 }; You need to use an integer B. You need to use B to save the address of the struct pointer (struct a * A = new A) so that the value of B is the address pointed to by, you may want to directly B = A, but the compiler will not a

Void pointer and void pointerVoid pointer indicates that the data type pointed to by this pointer in memory must be specified by the user.For example, the pointer returned by the memory allocation function malloc is the void * type,When using this pointer, the user needs to

In this paper, we mainly summarize the relevant principles and implementation of the smart pointers introduced earlier, and by the way, add the contents of the shared_ptr that are not mentioned in the previous article.Summarize:1. The smart pointer, through the RAII mechanism, constructs the object when the resource is initialized, and when the object is destructor, the resource is cleaned and Shanwei.2.auto_ptr, prevents the copy/assignment of object

First of all, we landed their QQ space, and then click on the top of the "Dress Up", "Dress Up Mall", "single product", "decoration", "mouse" (not friends, please see the picture of Kazakhstan) Next, find your favorite mouse pointer, select Good, we right-click on the pattern, and then select "Properties" (I choose the sea rays, haha) In the pop-up Properties window, we copy the address. (as pictured) Next, we do

I. pointer and address description:1. The address operator can only be applied to objects in memory, that is, variables and array elements. It cannot act on expressions, constants, or register-type variables.2. The unary operator * is an indirect addressing or indirect reference operator. When used as a pointer, the object to which the access Pointer Points3. poi

'The article was first published in shuimu Tsinghua BBS microsofttrd. Please keep the relevant information'Chen3feng (RoachCock@smth.org)'Email: chen3feng@163.com, chen3fengx@hotmail.com ''Well, I have been looking for this one day today. Fortunately, I met this and tried it. Yes.'2017-12-09 reference; Vb function pointer call of Matthew Curland'This method does not work if the parameter type is incorrect when the function has exit. Exit judgment, the