C + + study notes: Hello World

the first C + + program "Hello World"

As a student of C + +, I am honored to share My learning experience with all of you.

Where do we start? Start with the famous "Hello World". The code is as follows:

 //uses the VI editor under Linux for source code input, compile, and link using the GCC compiler. VC6 and VS can refer to their own compiler manuals. 
 1  #include <iostream>2  using  namespace   Std;  3   Main ()//note should be int main ()  4  { 5  cout<< hello World  Span style= "color: #800000;" > " <<ENDL;  6  return  0   7 } 

After writing the above code with the VI editor, compile, link, and execute it with the GCC compiler, you can see "Hello World" appearing on the screen. The first C + + program was born!
Now look back to write the source code, to probably see a C + + program composition.

First line of the first sign "#", what is this thing? This symbol is a preprocessing symbol in C + +, what is preprocessing? preprocessing refers to the processing of C + + source code by the preprocessor before the C + + program source code is compiled. The meaning of "include" is obvious, which means "import". Within a pair of angle brackets is the name of the file to import (iostream). The first line means: Import a file named iostream. The imported files are often called "header files" by C + + programmers, as iostream itself will be explained later, as long as it is clear that you want to output to the screen must have "iostream" this header file.

The second line uses a using statement, namespace means "namespace", Std is the name of that space! The namespace is described in more detail later. The second line means: Use the namespace Std.

int main () {/**/} is the main function of C + +, and a C + + program has only one main function as the entry point for C + + programs. int is the return value of the main function.

Cout is an object of the C++i/o Stream class library, meaning "output (to screen)". "<<" is a shift operator, which is described in the operator. "Hello World" is a "string", so-called "string" is "a string of characters." The function of the Endl is to wrap and refresh the stream. The specific meanings of cout, <<, Endl, and "flow" are described in the I/O library.

return 0; This statement: The main function returns the value of the return of the 0,main function as follows: Return 0 indicates that the C + + program is working properly, and if it returns non-0, it does not work properly. This return value is returned to the system.

#include < header files >

the int main ()//main function may have parameters

{

/* Function Body */

}

is the basic structure of C + + programs, and later our program basically follow this structure.

Note: 1. #include <iostream.h> is the C language style of writing, C + + is not recommended.

The standard return value of the 2.main function is int,void main () and is not recommended.

C + + study notes: Hello World