C language tutorial (1) - preparation

To start learning C language, you generally need to prepare:

• linux virtual machine download virtual machine
• gcc compiler (usually comes with linux)

As for how to install a virtual machine Baidu Yiyi I won’t say too much here.

So, how do you use a virtual machine?This requires some commands.

Right-click on the desktop, click open the terminal, you can enter commands in this interface.

Here are a few basic commands:

• mkdir + directory name create directory
• rm + filename delete file
• ls list files
• cp + file to copy + file after copy copy file
• ...

The basic usage of these commands can be obtained with the man command.

such as man mkdir

If you want to write c code, you can use the vi editor.Note that the c code ends with .c

vi + filename write file

vi has three modes:

• Command Mode
• Edit Mode
• Last line mode

The command mode is entered at the beginning, and no code can be written.At this point, click the "i" key to enter edit mode.In edit mode, you can write code.

Enter the following code in edit mode:

#includeint main(void){printf("Hello World");return 0;}

For the explanation of this code, we will gradually understand it later.in here

int main(void){return 0;}

It is often a framework for C code.

I believe everyone has experienced the pain of losing files without saving.So, how do we save the code we write?

First, we need to hit the Esc key to switch from edit mode to command mode.Then, click the ":" key to switch from command mode to last line mode.In the last line mode, enter wq to save and exit.

• w: save
• q: quit without saving

So, how to run this program?

After exiting vi, we are back where we entered the command before.In it, enter

gcc + filename

At this time, gcc will preprocess the c code (source file) we wrote (will be discussed later) and compile it to generate an executable file, the default is "a.out", to run the executable file, you need to input: ./+ filename.Running our "a.out", we can type

./a.out

Can I change the name of the executable to b.out?

The first method:

mv a.out b.out

What is mv?Enter the following command to view.

man mv

The second method, when generating the executable file, enter

gcc filename -o b.out

In this way, b.out can be directly generated as an executable file.

In addition, since man comes out in baby language, so Baidu translation