Execute Brain****/Java: Difference between revisions

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In this implementation of [[Brainf***]], the code is read in all at once and checked for uneven brackets (unequal amounts of [ and ] commands). If that error occurs, the code will obviously not be run.

Under the hood, the program memory is an ArrayList of Integers which expands only to the right. So, if the pointer moves past zero to the left, the program will exit and a "Pointer out of range" error message will be displayed. Due to the BufferedReader input class, return characters ([http://www.asciitable.com ASCII] 10 and 13) are ignored on input (the , command). ~~Return characters~~ are not ignored on output (the . command). More detailed information can be found in the comments scattered about the code.

Under the hood, the program memory is an ArrayList of Integers which expands only to the right. So, if the pointer moves past zero to the left, the program will exit and a "Pointer out of range" error message will be displayed. Due to the BufferedReader input class, return characters ([http://www.asciitable.com ASCII] 10 and 13) are ignored on input (the , command), but are not ignored on output (the . command). More detailed information can be found in the comments scattered about the code.

import java.io.BufferedReader;

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* The main program. Holds the input loop and error-handling.

*

* @param args 0: Source file others: ignored

*/

public static void main(String[] args){

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StringBuilder code= new StringBuilder();

//~~counts~~ for loop syntax errors

//count for loop syntax errors

int bCnt= 0;

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case '.':

System.out.print((char)memory.get(pointer).intValue());

//no errors possible here

break;

case ',':

input(memory, input);

//no errors possible here

break;

case '[':

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case '>':

pointer++;

//gets rid of NullPointerExceptions

while(pointer + 1 > memory.size()) memory.add(0);

break;

case '<':

if(pointer == 0){

//can't do it

System.err.println("Pointer out of range (negative).");

return;

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public static void jumpBack(StringBuilder code){

//initial count for the bracket we're on

//read back with pointer

⚫

//count brackets until the corresponding [

int bracketCnt= 1;

⚫

//count brackets until the corresponding [

while(codeIndex >= 0 && bracketCnt != 0){

codeIndex--;

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public static void jumpForward(StringBuilder code){

//initial count for the bracket we're on

//read back with code pointer

⚫

//count brackets until the corresponding ]

int bracketCnt= 1;

⚫

//count brackets until the corresponding ]

while(codeIndex < code.length() && bracketCnt != 0){

codeIndex++;