用C++编程实现计算带小括号和加减乘除（整除）的算术表达式

输入一个表达式，输出其值。
代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>

using namespace std;

struct Expression
{
    Expression *father;
    int top;
    long long number[101];
    char symbol[101];
    Expression *child[101];
}*p;

string expression;
int lenExpression;

long long Work(Expression *workExpression);

int main(int argc, char const *argv[])
{
    cin >> expression;
    lenExpression = expression.length();
    p = new Expression;
    p->top = 0;
    p->father = NULL;
    memset(p->symbol, 0, sizeof(p->symbol));
    memset(p->number, 0, sizeof(p->number));
    for (int i=0; i<lenExpression; i++)
    {
        if (expression[i] == '(')
        {
            (p->top)++;
            p->child[p->top] = new Expression;
            p->child[p->top]->father = p;
            p = p->child[p->top];
            p->top = 0;
            memset(p->number, 0, sizeof(p->number));
            memset(p->symbol, 0, sizeof(p->symbol));
        }
        else if (expression[i] == ')')
        {
            p = p->father;
        }
        else if (expression[i]>='0' && expression[i]<='9')
        {
            if (p->child[p->top]!=NULL or p->symbol[p->top]!=0 or p->top==0)
            {
                (p->top)++;
            }
            p->number[p->top] = (p->number[p->top])*10+(expression[i]-'0');
            p->child[p->top] = NULL;
        }
        else
        {
            (p->top)++;
            p->symbol[p->top] = expression[i];
            p->child[p->top] = NULL;
        }
    }
    while (p->father != NULL)
    {
        p = p->father;
    }
    cout << Work(p) << endl;
    return 0;
}

long long Work(Expression *workExpression)
{
    long long ans = 0;
    for (int i=1; i<=workExpression->top; )
    {
        if (workExpression->child[i] != NULL)
        {
            workExpression->number[i] = Work(workExpression->child[i]);
            workExpression->child[i] = NULL;
        }
        if (workExpression->child[i]==NULL and workExpression->symbol[i]==0)
        {
            if (i >= 3)
            {
                if (workExpression->symbol[i-1] == '*')
                {
                    workExpression->number[i-2] *= workExpression->number[i];
                    for (int j=i-1; j<workExpression->top-1; j++)
                    {
                        workExpression->child[j] = workExpression->child[j+2];
                        workExpression->number[j] = workExpression->number[j+2];
                        workExpression->symbol[j] = workExpression->symbol[j+2];
                    }
                    workExpression->top -= 2;
                }
                else if (workExpression->symbol[i-1] == '/')
                {
                    workExpression->number[i-2] /= workExpression->number[i];
                    for (int j=i-1; j<workExpression->top-1; j++)
                    {
                        workExpression->child[j] = workExpression->child[j+2];
                        workExpression->number[j] = workExpression->number[j+2];
                        workExpression->symbol[j] = workExpression->symbol[j+2];
                    }
                    workExpression->top -= 2;
                }
                else
                {
                    i++;
                }
            }
            else
            {
                i++;
            }
        }
        else
        {
            i++;
        }
    }
    char sbl = '+';
    for (int i=1; i<=workExpression->top; i++)
    {
        if (workExpression->symbol[i] == '+')
        {
            sbl = '+';
        }
        else if (workExpression->symbol[i] == '-')
        {
            sbl = '-';
        }
        else
        {
            if (sbl == '+')
            {
                ans += workExpression->number[i];
            }
            else
            {
                ans -= workExpression->number[i];
            }
        }
    }
    return ans;
}