C language -- 1 c language cognition

Recent preparation and improvement C Language learning , Consolidate foundation .

1、c The content of language learning

• Understand what is c Language
• data type
• Variable 、 Constant
• character string 、 Escape character 、 notes
• Select statement
• Loop statement
• function
• Array
• The operator
• Common keywords
• define Define constants and macros
• The pointer
• Structure

2、 What is? c Language

Language ： People communicate with people
Computer language ： The language in which people communicate with computers , Such as ：c、c++、JAVA etc.
c Language is a general computer programming language , Widely used in underlying development （ namely ： Write operating system 、 Drive, etc ）.C The design goal of the language is to provide a way to compile 、 Processing low-level memory , Generate a small amount of machine code and a programming language that can run without any running environment support .

C Language has international standards , Such as ：c89,c90,c99,c11, Mainly c89 And c90.

3、 How to write c What about the language code ？

Write through the compiler , Its compiler mainly includes ：Clang,GCC,WIN-TC,SUBLIME,MSVC,Turbo C etc. . This study is going to use microsoft visual studio 2022, It's the integrated development environment , Integrated MSVC Such a compiler , You can write and compile c The language code .
Write c Procedure steps ：

• Create a project
  

• Create a source file
  

• Write code , Write a simple one first , Print “c Language learning ”, Write the main function （main function ） And the body of the function

{
    
	return 0;// This part is the body of the function 
}
 

#include<stdio.h>
int main() //int Is the type returned by the function ,main（） Is the function name 
{
    
	printf("c Language learning ");
	return 0;
}

• Compile code + Run code
  On the menu bar — debugging — Start execution without debugging ;
  Shortcut key fn+ctrl+f5
  Shortcut key ctrl+f5

4、 How to execute c Code ？

• c The language is executed from the first line of the main function , therefore c Language code lines must have main function ,main Function is an entry , Otherwise, you can't execute .

• printf It's a library function , To print information on a screen ,printf The use of is required in advance “ Say hello ” Of , namely ： Is to include the header file ,#include <stdio.h>

• Set item properties ： Stop “ project ” name — Right click “ attribute ”—“ The linker ”—“ System ”—“ Subsystem ” Change the back to “ Console …”
  

• Be careful ： There can be multiple in a project .c file , But these multiple .c The file has and can only have one main function