dStack("operandStack ");
    ArrayStack operatorStack("operatorStack");
    int streamLen = strlen(buffer);
    char c;
    /*
     * 需要归约的情况:
     * 1. 当前的token是整数, 且操作符栈顶元素为''*''或''/'';
     * 2. 当前的token是'')'';
     * 3. 当前的token是''+''或''-'', 且操作符栈顶元素为''+''或''-'';
     */
    for(int index=0; index<streamLen; index++){
        c = buffer[index];
        Token t;
        if(c >= ''0'' && c <= ''9''){
            t.type = Token_Int;
            t.value = c - ''0'';
            operandStack.push(t);
            if(!operatorStack.isEmpty()){
                if(operatorStack.peek()->type == ''*''
                        || operatorStack.peek()->type == ''/''){
                    calculate(operandStack, operatorStack);
                }
            }
        }else{
            t.type = c;
            Token *temp;
            switch(c){
                case '')'':
                    if(operatorStack.isEmpty()){
                        printf("*********Syntax Error!*********\n");
                        exit(0);
                    }
                    temp = operatorStack.peek();
                    if(temp->type == ''