Im looking over a piece of Java code I didn't write and noticed that it included & in it in a few places. Its a piece of code from a infix to postfix notation converter.
If I put this piece of code in Eclipse it dosn't like these &s and creates errors for them, the error being & cannot be resolved as a variable.
Heres the code
public static String[] infixToRPN(String[] inputTokens) { ArrayList<String> out = new ArrayList<String>(); Stack<String> stack = new Stack<String>(); // For all the input tokens [S1] read the next token [S2] for (String token : inputTokens) { if (isOperator(token)) { // If token is an operator (x) [S3] while (!stack.empty() && isOperator(stack.peek())) { // [S4] if ((isAssociative(token, LEFT_ASSOC) && cmpPrecedence( token, stack.peek()) <= 0) || (isAssociative(token, RIGHT_ASSOC) && cmpPrecedence( token, stack.peek()) < 0)) { out.add(stack.pop()); // [S5] [S6] continue; } break; } // Push the new operator on the stack [S7] stack.push(token); } else if (token.equals("(")) { stack.push(token); // [S8] } else if (token.equals(")")) { // [S9] while (!stack.empty() && !stack.peek().equals("(")) { out.add(stack.pop()); // [S10] } stack.pop(); // [S11] } else { out.add(token); // [S12] } } while (!stack.empty()) { out.add(stack.pop()); // [S13] } String[] output = new String[out.size()]; return out.toArray(output);
}6 Answers
You are copy pasting code from a badly encoded website. This & should be replaced with an ampersand (&).
In HTML, you cannot simply write &, because that is an escape character. So, in history, they invented the escape sequence for ampersands, which is: &. That is what the website is showing you unfortunately.
So, to answer the question: && should be: &&. That is the logical AND operator.
This looks like an encoding problem with the source file.
& is the ampersand character from the ISO-8859-1 character set.
That looks like a mis-encoding of a Java file. I'm only aware of the && operator, which is logical AND.
& is the HTML escaped version of &.
You should replace all & with &
There is no & in java, it's obviously a result of copy-paste from an HTML page. Replace & with & to fix it.
In Java you have:
- boolean AND -->
&& - bitwise AND -->
&
Your issue is that your code contains XML entities that haven't been successfully decoded, so & means &, just as > would mean >.
