Embedded engineers should make good use of the three elements of C language

  As an embedded Engineer , How to write efficiently 、 Clear thinking C What about language programs ?

• Use C Language thinking mode to construct the framework of the program

• Have a good C Fundamentals of language algorithms , In order to realize the logical framework of the program

• Flexible use of C Pointer operation of language

     Although it seems that the above statement is very abstract , It feels like falling into the fog , In fact, it is to use C There is a problem with language 、 The process of analyzing and solving problems .

     Embedded engineers are writing C When it comes to language programs , We should build the program architecture for the problems encountered .

     For example, we have to deal with “ Monkey chooses King ” The classic question of ： A group of monkeys , Form a circle hand in hand , Start with any monkey 1 Start counting , When you encounter a number to exclude ( Preset ) When the monkey exits the circle , Start with the next monkey and continue from 1 Number off , So again and again , Finally, the remaining monkeys are the king of monkeys .

use C The thinking mode of language is used to construct the program framework

     The program is divided into three parts ：

a、 Data acquisition , In order to run the program , The above question is to get the total number of monkeys , Start with the monkey and eliminate the number ;

b、 Data operation , You need to eliminate the corresponding data from a pile of data , Pay attention to the correctness of logic ;

c、 Increases the speed of the program , Use fewer loops and more pointers .

use C Language for logical implementation

a、 Data acquisition , adopt printf and scanf Get the parameters .

  At the same time, pay attention to the handling of exceptions , Like the two above if A statement is the judgment of an exception , Each exception corresponds to a different return value , This facilitates the debugging of the program process and the legitimacy of the data .

b、 /* Define the node type of the linked list */

      Build a circular linked list for “ monkey ” Circle construction .

  After this step ,head and p(present) Has become a “ Monkey ring ” The linked list of . In the process of building the linked list, we need to pay attention to the following points ： Memory development , At this time, the principle of how much to use and how much to open up .

     If you open up too much at once , Can cause memory leaks , however , This small program will not encounter this problem . The second is to be familiar with the construction method of circular linked list ： The tail of the list points to the head of the list . At this time, if you want to, you will also think of the situation of two-way linked list .

c、 /* Find No k Nodes */

  Find where to start counting . here ,p Point to the beginning “ monkey ”. Because the linked list method is used , This process only needs to focus on p Pointer next Just point .

a、 Save the initial “ monkey ” Circle parameter .

   Why keep this ? First, control the number of monkeys , So keep all the numbers . Next use q(qurry) To keep the linked list in front of the monkey , And connect the linked list after removing monkeys . such , Completed the element deletion of the circular linked list .

b、 Monkeys count .

     Monkey counting is the key to the whole program , The following tasks need to be completed ：a、 Find the beginning “ monkey ” Count ;b、 Delete the “ monkey ”;c、 Connect the head and tail of the deleted circular linked list .

  Through the above data operation , You can delete the corresponding linked list elements , This may be C The charm of language programs .

Use C The pointer to language

     For example, the definition of the linked list pointer of this program ,p,s,q.

  We know , Pointer operation can not only reduce the memory required for data operation , It can also improve the running speed of the program .

     The advantages of pointers , Perhaps it is not obvious in this procedure , In the case of a large amount of data and sensitive to the requirements of operation speed, it will be obvious , such as Linux The kernel , There will be a good embodiment .

     All in all , For embedded engineers , Not only can we design good hardware circuits , If we can write good software programs, our life will be better .

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【 Share some learning materials below , You can see what you are interested in 】：

Internet of things embedded engineer network foundation

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  Embedded application lightweight database .

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【 Share some online disk information packages below , If you need it, you can collect it yourself 】：

Embedded Internet of things 22 individual STM32 project 、 Competition works ,【 Huaqing vision issued the information package 】http://makerschool.mikecrm.com/f4wjYBB