C++ Hello World Broken Down

Let’s look at this hello world C++ program broken down line by line.

// A Hello World program
#include <iostream>
 
int main()
{
	std::cout << "Hello, world!\n";
	
	return 0;
}

Line by Line

// A Hello World program

• the // symbol indicates that the rest of the line is a comment, meant for human readers and ignored by the compiler.

#include <iostream>

• the # refers to a preprocessor directive, which is handled before actual compilation.
• include tells the preprocessor to include the contents of a file here.
• <iostream> is the name of the file being included, which provides functionality for input and output streams.

int main()

• int indicates that the function returns an integer value.
• main is the name of the function where execution starts.
• () indicates that this function takes no parameters.

{

• the opening curly brace { marks the beginning of the function body.

std::cout << "Hello, world!\n";

• std::cout is the standard output stream in C++.
• << is the stream insertion operator, used to send data to the output stream.
• "Hello, world!\n" is a string literal that contains the text to be printed, followed by \n, which represents a newline character. \n is an escape sequence.

return 0;

• indicates that the program should tell the operating system it has completed successfully.

}

• the closing curly brace } marks the end of the function body.