将 int 存储到 char 数组中

Question

I have these set up at the top of the method.

public static String eval(char[] postfix) {

    StackInterface<Character> stack = new LinkedStack<>();

    char[] answer = new char[postfix.length];

    int numOne = 0;
    int numTwo = 0;
    int result = 0;
    int i;

    for (i=0; i < postfix.length; i++)
    .....

Down the line I have done this:

    if (!stack.empty()) {
       numOne = stack.top();
       stack.pop();

       numTwo = stack.peek();
       stack.pop();

       //My problem is here. I can't push the result to my char[] array.

       if (postfix[i] == '+') {
           result = numOne + numTwo;
           stack.push(result);
       ..........

How do I set it up so that I can push the result of the two pop() 'd variables to my char[] array?

Answer 1

You need too read them as Character (or char), not int; The stack is working with Character, there is no reason to read the values into integer. Like:

char numOne = 0;
char numTwo = 0;
char result = 0;
...
 result = numOne + numTwo;
 stack.push(result);

Note, there could be additional problem with the char range of the sum result.

Answer 2

You should cast the result to a char, because if you use the method stack.push(int) , the int will not be converted automatically. Instead do this: stack.push( (char) result ); The result will be casted to a char. Assigning an int value to a char is valid, because while assigning it, Java automatically casts it.But if you use an int as argument of a method instead of a char, Java wouldn't do that.Sorry for bad English, but more easily: Working:

char c = 364; //the int value is automatically converted

Not working

public void doSomething(char c) {..}    
doSomething(534);    //here the int will NOT be automatically casted to an int

Second example in a valid way

doSomething( (char) 534); 

In less words, you should push a casted int. The (char) is your friend

Note: you can encounter failures if the sum between the two ints is higher than the maximum char value available.