未处理的异常？？ if语句的微小错误似乎无法解决

Question

所以这个项目需要输入U，M或D以及你喜欢的任意数量（我认为，基于代码中的charUMD [100]数组可能只有100个），你必须结束用＃来表示结束。我想说，如果你不包括＃，那么程序应该输出错误消息错误：字符串不会以＆＃39;＃＆＃39;！如在主要的if语句中所见。然而，由于＆＃34;超出范围＆＃34;它给了我未处理的异常错误。我该如何解决这个问题？

#include <iostream>
#include <string>
#include <vector>

using namespace std;

int length;

char UMD[100];
char value;
int i = 0;
string list;

void SWAP(char s[], int i, int j)
{
    char x, y;
    x = s[i];
    y = s[j];
    s[j] = x;
    s[i] = y;
}

void sort(char s[])
{
    for (int c = 0; c < (i - 1); c++)
    {
        for (int d = 0; d < i - c - 1; d++)
        {
            if (UMD[d] <= UMD[d + 1]) /* For decreasing order use < */
            {
                SWAP(UMD, d, (d + 1));
            }
        }
    }
}

int main()
{
        cout << "TYPE U, M, or D for the array" << endl;
        cout << "Type any other letter to stop adding!" << endl;

        cin >> list;
        int o = 0;
        while (list[o] != 0)
        {
            i++;
            o++;
        }

        int p = 0;
        while ((list.at(p)) != '#')
        {
            UMD[p] = list.at(p); p++;
        }

        if (UMD[o] != '#'){ cout << "Error: String Does Not End With '#'!" << endl; system("pause"); exit(0); }//<------IF UMD[o] is not '#', then it should display this message! However it does not work for '#' IDK WHY!

        for (int z = 0; z < p; z++)
        {
            if (list.at(z) != 'U'&&list.at(z) != 'M'&&list.at(z) != 'D')
            {
                cout << "Error: character other than U, M, or D provided" << endl; system("pause"); exit(0);
                cout << list.at(z);
            }
        }

        sort(UMD);
        cout << endl;
        cout << "Here is the sorted version of the array" << endl;
        for (int z = 0; z < i; z++)
        {
            cout << UMD[z];
        }

        cin >> list;

    system("pause");
    return 0;
}