HQ9+

HQ9+ is a joke language with four instructions:

• H: Print "hello, world"
• Q: Print the program's source code
• 9: Print the lyrics to "99 Bottles of Beer"
• +: Increment the accumulator

Although the language is not of serious interest by itself, it can be useful to implement HQ9+ in a new esoteric programming language, since doing so proves that all the tasks above, except the quine, are possible. (Implementing Q proves instead that a cat program is possible.) HQ9+ was created in 2001 by Cliff L. Biffle.

Given that the original description of the language includes an example program containing a lowercase "q", it seems reasonable to assume that instructions in HQ9+ are case-insensitive.

Implementation

User:A was here and here is an implementation (in C):

#include <stdio.h>
int main()
{
    unsigned long accumulator = 0;
    char c[1000];
    for(int i=0;;i++)
    {
        scanf("%c",&c[i]);
        if(c[i]=='\n') break;
    }
    for(int i=0;c[i]!='\0';i++)
    {
        if(c[i]=='H') printf("Hello, World!\n");
        else if(c[i]=='Q') printf("%.*s", (int)sizeof c, c);
        else if(c[i]=='9')
        {
                for(int j=99;j>0;j--)
                {
                    printf("%d bottles of beer on the wall,\n%d bottles of beer.\n", j, j);
                    printf("Take one down, pass it around,\n%d bottles of beer on the wall.\n", j-1);
                }
                printf("1 bottle of beer on the wall,\n1 bottle of beer.\nTake one down, pass it around,\nno more bottles of beer on the wall.\n");
        }
        else if(c[i]=='+') accumulator++;
    }

    return 0;
}

Lanmonster fixed the Q instruction and added the + instruction. Qh4os fixed the 9 instruction. Chris Pressey also fixed the 9 instruction.

See also

• HQ9++, an object-oriented extension of HQ9+.
• HQ9+-, an extension of HQ9++ with the - operator for debugging purposes.
• HQ9+~, an extension of HQ9+ which is Turing-complete.
• HQ9F+, an extension of HQ9+ with the F operator for FizzBuzz.
• FHQ9+-, an extension of HQ9+- with the F operator for FizzBuzz.
• CHIQRSX9+, another HQ9+ extension supposedly Turing complete.
• HQ9+B, an ℒ-complete extension of HQ9+.
• HQ9+2D, a 2-D extension of HQ9+.
• H9+, with one fewer instruction but still capable of all of the tasks.
• FISHQ9+, HQ9+ and deadfish combined.
• HI9+, which replaces Q with an instruction that prints the interpreter's source code.
• +, where there is only +, and other characters are ignored.
• Hq9eFuck, HQ9+, brainfuck and Deep Thought combined.
• BrainfisHQ9+, HQ9+, brainfuck and deadfish combined.
• ACHEQUEUENINETHOUSANDPLUS, a more powerful derivative.

External resources

• HQ9+ home page (from the Wayback Machine; retrieved on 2 June 2009)
• HQ9+ as an embedded language in Haskell
• Online HQ9+ interpreter in JavaScript (from the Wayback Machine; retrieved on 23 April 2006)
• Online HQ9+ interpreter realized with PHP
• HQ9+ interpreter in C by User:mmphosis
• HQ9+ interpreter in Pascal by User:GrandKeyboard (dead link)
• hq9plus - HQ9P implementation for Parrot
• HQ9+ Interpreter - HQ9+ interpreter written in Kotlin by User:Timleg002