Learning C language today is the first time to learn C language. In college, C linguistics is not good, but I want to make progress, so I found a beep video on the Internet to learn C language

First we learn to use visual2017, I use 2017, We first learn how to use this software .

First we open a file —— newly build —— project

We click on the icon once

  Then we need to find the Solution Explorer , You can find it in the view , The first one is .

  Right click the source file , Click new item

We click c++ Please note that the following names must be used .cpp, Click ok

  Then we can write the program , The first program I wrote was learned from watching the video , The contents are as follows

here main It's the main function ,C The language program is executed from main The first line of the function starts executing , there printf Function is a library function , We can print the characters we want to output on the public screen . Our computers do not have this function , So we need a header file called stdio.h Find this library file in the header file of . We can use #include<> Method to include this header file .int Is the return function type ,main Is the function name , Brackets {} The content in is the function body . After we have written it, we need to run the program , We can do that by using ctrl+f5 The way to run .

Some versions of visual studio Because of the direct operation, we will not see the results of the operation , But that doesn't mean the computer isn't running , We can find the Solution Explorer as shown in the picture , Right click on our project , Find the system of the connector in the properties , Click the console in the subsystem （ my visual studio2017 The default is console ）

  It is worth noting that there is only one in a project main function , Multiple... Are not allowed main function , because main The function is equivalent to a vertical entry , When there are multiple vertical entrances in our project, the computer program does not know which one to enter from, so it will report an error , There can be more than one in a project .c Program , But many .c There can only be one in the program main function .

So that's the end of the first program , At the end of writing the program, I found a problem , I don't understand why there should be one return function , And why in return Followed by 0 Well , I'll start with 0 Change to 1, Discovery works , The only difference is that the return code is 0  Changed to 1. Later, I tried a few more numbers and found that they were all OK , Add more in the middle space Spaces are also OK , Even delete return 0 It's OK, too , But you can't change it into letters . So I looked up the information on the Internet .

 

  What I mean here is return A function is when we run a program , Internal functions return You can exit the function and set the value to the number we need .return 0 The return value is 0,,return  The return value is 1. That's all for today's study , I hope we'll see you next time , I hope I can stick to it all the time .