Provided by Chengdu control panel design_ It's detailed_ Introduction to the definition, compilation and quotation of single chip microcomputer program header file

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Don't panic when you are confused at first , The sunrise fog dispersed and the road was bright .

This article introduces the definition of 、 To write 、 Save and quote content , Including general format requirements 、 Routine, etc .

What is a header file ？

Header file in C Language is generally necessary in program development , Generally in C The header file must be referenced at the beginning of the program .

Header file as a function containing functions 、 Carrier file for data interface declaration , Mainly used to save the declaration of the program , The definition file is used to save the implementation of the program .

Why use header files ？

If there is no header file , Then the definition is only in C In file , There are several disadvantages ：

-> Not easy to read . Put the definition and function code together , Poor readability ;

-> Repeated labor , Increase the number of programs . In all C In file , As long as you use it, you have to redefine , There will be more duplicate code, etc .

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What are the general format requirements for writing header files ？

 

Many things have formats , Do it according to the format. Generally, there will be no error . chart 1 The general structure defined for the header file .

At the beginning #ifndef And the last #endif You need to be in pairs , It means that if a file is not defined , Then perform some operations . stay #ifndef and #endif You can write the code defined by the header file , If other header files are loaded 、 Pin definition 、 Subroutine predefined, etc .

The following table shows the diagram 1 Explanation of some codes in .

surface 1 chart 1 Explain the main points of

#ifndef __XXX_H__ … #endif	If there is no definition XXX.H, Then do something . If and endif Must be used in pairs .
#define __ XXX _H__	Definition XXX.H
#include <xxx.h>	Load the relevant system header file xxx.h
#include “yyy.h”	Load the relevant custom header file yyy.h
sbit x=p;	System bit definition . Generally used to define pins , use x Instead of pins p.
#define  X Y	Symbolic variable definition ,X It means Y value .Y Generally, it is a specific value .X and Y There's a space between
void XX();	Subroutines are predefined . After loading this header file in other programs , Can call XX Subroutines . Predefined in the corresponding C Specific subroutine code has to be written in the document .

An example of header file writing

  There's an example , There will be a more vivid understanding . chart 2 An example defined for a header file , The name bit of the header file relaycontrol.h, This header file contains loading other header files 、 Pin definition 、 Symbolic variable definition 、 Subroutine predefinition, etc .

Save method of header file

Save header files generally have 2 Methods ：

（1）、 stay keil Kept in H file ： For example , If be in, keil New in H file , After writing the header code , Click the save button , Name it and save it on the computer hard disk （ With the reference to it C The files are in the same folder ） It's OK , The header file saved in this example is relaycontrol.h.

（2）、 Create a new one in your computer TXT file , Change the extension to .h： On the computer hard disk （ With the reference to it C The files are in the same folder ） Create a new one in txt file , Write header file code , preservation , And change the extension to .h. In this case, this txt Change the file name and extension to relaycontrol.h.

How the C Reference header file in program ？

 

stay C In the program , You need to reference the header before you can use it , Generally, the reference header file is placed at the beginning of the program .

stay C The method of referencing header files in files is very simple , Is to use... In the program “#include” Command to load the corresponding header file .

After reference , In this C The content defined in the header file can be used in the file , As defined by pin 、 Symbolic variables and subroutines .

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At the end of this section , Wonderful to be continued .