c语言指针入门(Introduction to C language pointers).doc
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1、c语言指针入门(Introduction to C language pointers)Pointer C programming language entry (thirteen)- Li Changlin, head office of soft Corporation-Using pointers is one of the most important features of C language. What is a pointer? A pointer is a variable class that holds the address of memoryType. That is
2、 to say, the pointer is used to specify the location of a variable in memory. Or, the pointer is pointing to anotherA variable. The pointer and the address are closely linked together.This shows that it may be difficult for beginners to understand, and the library below is an example of what a point
3、er is.In the library, the library in every book there is a whole stack of press ISBN, ISBN aligned. CodesCan be regarded as the address of the book in the library. Each book also has an index card to find a book, first from an index cardTo find this book ISBN, then press ISBN book in the library. Th
4、is process instruction number indicates the location of the book in the librarySet, that is, the address. The book is an index card pointer variable, on top of it is the memory address book number. And that numberThe book on the location of the code is the variable it refers to. Thus, you can also i
5、ndicate the pointer: index card (pointer). This variable isTo indicate the location of a Book (a variable) in a stack (in memory); or index cards (pointers) that point to a BookA variable (another variable).Pointers manipulate variables through the indirect address of the memory address. With pointe
6、rs, this data type can be more complex to generateData structures, such as linked lists, two tree, etc., can make some complex data, such as array, structure, union and other dataThe transfer and operation of functions becomes easy, and the compiled target code can be executed faster and more effici
7、ently. becauseThis study C language, the concept of pointer must understand, correct use.First, the definition of the pointer, form, type identifier * pointer name;Type identifier: the data type of the object to which the pointer is specified. For data types, it can be basic dataType can also be an
8、extended data type.*: represents the pointer operator. It has two functions: first, to define pointer variables, and two to specify the values of the variables referred to by the pointer.Pointer Name: Specifies the user specified name identifier in accordance with the C language.Example 1:Char *ch;T
9、he ch pointer is defined, which refers to the character type variable.Example 2:int *n;The N pointer is defined, which refers to integer variables.Example 3:float *5 pointer, which refers to a single precision floating point variable.Example 4:int (*p) 10;The P pointer is defined. It is a pointer to
10、 an array. There are 10 elements in the array, each of which is integer.Example 5: int *p10;Defines an array of P, with 10 elements in the array, each of which is a pointer to an integer variable.There are many more complicated definition examples of pointer, which will be explained in detail later.
11、 The reading of the pointer is:Read the name of the pointer first, read the name to the right, and then read the name of the pointer to the left. If you need to read the pointer first, read the left side and the right sideWith parentheses. Example 4.In addition, the keyword far or near may be added
12、before the type identifier and the * number to indicate the distant pointer or the near pointer.Example int far *n;This example defines a far pointer to N, it is pointing to an integer variable.The length of a pointer is dependent on the type of data it refers to. For example, int *n; two bytes on a
13、 general system. And intfar *n; four bytes.Two, pointer operationWhen the pointer is operated, first, the following two operators are shown as follows:- - the address operator, which returns the address of operands. You may ask questions & arent they by bitwise and operator?What is the address opera
14、tor? Yes, the C language allows you to define an operator repeatedly, and never confuse it when using it.* pointer operator, also referred to as indirection operator. In operation, it returns the value of the variable in the pointers positionWhen a variable is called, it indicates that this variable
15、 is a pointer. We can see this is a duplicate definition (and sign (*) is repeated). butWhen used, it is not confused because of the different positions in the program. C language definition and repeat operator, such as minus (-) and minus (-).Such as:Int n=5;* defines the integer variable n initial
16、 value 5*/int *p; / * P defines a pointer, which points to integer data */p=&n;* the variable n address assigned to the p*/printf pointer (N=%d, P points to the value of the variable =%dn, N, *p);Display results: N=5, P points to the value of the variable =5The above four statements illustrate the b
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