javascript使用棧結(jié)構(gòu)將中綴表達(dá)式轉(zhuǎn)換為后綴表達(dá)式并計(jì)算值

//使用數(shù)組dataStore保存站內(nèi)元素，構(gòu)造函數(shù)將其初始化為一個(gè)空數(shù)組。
//變量top定義棧頂?shù)奈恢茫瑯?gòu)造時(shí)初始化為0，表示棧的起始位置為0
function Stack(){
    this.dataStore = [];
    this.top = 0;
    this.push = push;
    this.pop = pop;
    this.peek = peek;
    this.clear = clear;
    this.length = length;
    this.printElement = printStack;

    //注意++操作符的位置，它放在this.top的后面，這樣新入棧的元素就被放在top的當(dāng)前位置對(duì)應(yīng)的位置，同時(shí)top自加1，指向下一個(gè)位置
    function push(element){
        this.dataStore[this.top++] = element;
    }
    //返回棧頂元素，同時(shí)top的位置減1
    function pop(){
        return this.dataStore[--this.top];
    }
    //peek()方法返回?cái)?shù)組的第top-1個(gè)位置的元素，即棧頂元素
    function peek(){
        return this.dataStore[this.top-1];
    }
    //將top的值設(shè)置0，即清空一個(gè)棧
    function clear(){
        this.top = 0;
    }
    //返回變量top的值即為棧內(nèi)元素的個(gè)數(shù)
    function length(){
        return this.top;
    }
    
    //輸出棧內(nèi)元素
    function printStack(){
        while (this.top>0){
            document.writeln(this.pop()+"  ");
        }
    }
}

/*-------------------棧將中綴表達(dá)式轉(zhuǎn)換成后綴表達(dá)式-------------------*/
document.write('<br><br>');
function suffixExpression(){
    var str = 'a+b*c+(d*e+f)*g';
    var stack = new Stack();
    var outStack = new Array();
    for (var i=0; i<str.length; ++i) {
        if(')' == str[i]){
            while (true){
                var top = stack.peek();
                stack.pop();
                if('(' != top){
                    outStack[outStack.length] = top;
                }else{
                    break;
                }
            }
        }else if(['-','+'].indexOf(str[i])>-1){
            if(['*','/'].indexOf(stack.peek())>-1){
                while (['*','/'].indexOf(stack.peek())>-1){
                    outStack[outStack.length] = stack.peek();
                    stack.pop();
                }
                outStack[outStack.length] = str[i];
            }else{
                stack.push(str[i]);
            }
        }else if(['(','*','/'].indexOf(str[i])>-1){
            stack.push(str[i]);
        }else{
            outStack[outStack.length] = str[i];
        }        
    }
    
    for (var i=0; i< outStack.length; i++) {
        document.write(outStack[i]);
    }
    

}
suffixExpression();
/*-------------------用棧結(jié)構(gòu)求后綴表達(dá)式的值-------------------*/
document.write('<br><br>');
function countSuffixExpression(){
    var str = '6523+8*+3+*';
    var stack = new Stack();
    for (var i=0; i<str.length; i++) {
        if(isNaN(str[i])){
            stack.push( eval( stack.pop() + str[i] + stack.pop()) );
        }else{
            stack.push(str[i])
        }
    }
    
    document.write(stack.pop());
}
countSuffixExpression();