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This article introduces the knowledge of "how to link two lonely structural variables in C language". In the operation of actual cases, many people will encounter such a dilemma. Next, let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

The first thing we need to know is that structure pointers can be used as internal member variables of a structure type. Suppose we have a student_t structure type that can contain a structure variable defined by itself. As shown in figure 1.

Figure 1 when defining a structure, add a structure pointer of its own type

As shown in figure 1, we can retain the tag option for the structure when we use typedef to define the structure storage type. This tag can be defined in conjunction with struct when defining pointers to structures of this type. Well, we have now defined a structure of type student_t. One of the most striking features of this structure is that its member variables contain a pointer to its own (student_t) type. Here's a hypothesis. Assuming that Xiao Ming and Xiao Li are students in the same class, we can define two structural variables to store their names and ages, as shown in figure 2.

Figure 2 print the information of Xiao Ming and Xiao Li

Now we can think about it again, if we want to establish a relationship, that is, the classmate sitting behind Xiao Ming, her name is Xiao Li, in other words, whether we can find a relationship and find Xiao Li's information through Xiao Ming. The answer is yes. We can see that the structure used to describe Xiao Ming also contains a structure pointer * next. Because the structure types used to describe Xiao Ming and Xiao Li are exactly the same, * next pointer can point to Xiao Li structure. As shown in figure 3.

Fig. 3 next structure pointer points to another structure variable

The pointing operation of this pointer can be implemented in code by assigning the first address of the XiaoLi structure to the Xiaoming.next. After doing this, the next pointer of Xiaoming points to XiaoLi, and we can easily query the relevant information of XiaoLi through Xiaoming. It should be noted here that Xiaoming.next is a structure pointer, so when you use the Xiaoming structure to query XiaoLi information, you need to use the point operation of Xiaoming.next, that is, Xiaoming.next- > name, and Xiaoming.next- > age. The specific code is shown in figure 4.

Fig. 4 print the information of a structure variable using next pointer

Now let's expand this information a little bit, assuming that two more buddies, called MaLi and JieKe, have been added to the group Xiaoming and XiaoLi. Then we can also use the same way to store MaLi and JieKe information, and use next pointers to "concatenate" their information one by one. As shown in figure 5.

Figure 5 use Xiaoming to print out the information of all the students

The above printf function is still troublesome to write the program. We need to write four different printf functions for these four students. If the number of students reaches 100, we also need to write 100 printf? So is there any way to print out the information of the whole connected structure just by writing a printf? The answer is yes again, let's take a look at the relationship between these structures. As shown in figure 6.

Fig. 6 the relationship between the four structures

If we want to be able to print out all the information about these four or more structures with only one sentence printf, when we think of learning arrays, there is an operation called array traversal that is similar. If we take a closer look at these structures, we can easily find a judgment condition, and the next pointer of the last structure is bound to point to NULL. So using this, we can define a student_t structure pointer seek, which first points to the first structure variable, and when the output is complete, points to the second structure variable, that is, the first next pointer is assigned to the seek pointer, and so on. When the last next is assigned to the seek pointer, the value of the seek pointer is bound to be NULL, so you can exit the entire loop. The specific code is shown in figure 7.

Fig. 7 seek pointer variable these four structural variables

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