A word of warning, this article is not for the faint of heart.

#include <iostream>
using namespace std;

int main(int argc, char *argv[]) {
	cout << "Hello, World!\n";  // about time we make it a little interesting
	cout << "\110\145\154\154\157\54\40\127\157\162\154\144\41\12";
	cout << "\x48\x65\x6C\x6C\x6F\x2C\x20\x57\x6F\x72\x6C\x64\x21\xA";
	return 0;
}

All three cout statements will print the same thing i.e., Hello, World!.

Now coming to the “how” part; in a nutshell, it has to do with escape sequences. Basically, they are used to represent characters which have special meaning in the language. For example, if we want to have a double quotation mark (") within some string literal we can’t have it directly, instead first we need to have a backslash (\) precede it. Also, there many escape sequences like \n, \t, etc. which are predefined by the language.

But that is not all there is to them, we can have escape sequences of octal and hexadecimal digits as well. Below is a list of two such obscure sequences:

• \ followed by one, two or three octal digits
• \x followed by one or more hexadecimal digits

The value that follows \ and \x represents the numerical value of the character. To keep it simple, let’s assume the language uses ASCII character encoding. In simple terms, it means every character that is used in the language is associated with a predefined numercial value as per the ASCII specification. The second and third cout statements use nothing but those values in octal and hexadecimal format respectively, to represent the corresponding characters.

• If there are more than three octal digits after \, then only the first three are considered, the remaining are considered as simple characters in a string.
• The hexadecimal digits are not case sensitive, \x6C is same as \x6c.

The table below summarizes all the characters in "Hello, World!\n", but it can be generalized to any string.

Hope you enjoyed this article. See you next time.