String-problem

hello

i have a CString where i check sign by sign using GetAt() to see if a sign is a digit. if it is a digit i want to copy it to another CString object

this is my code (part of it)

m_my and temp is CString

Code:

---

for(something)
{
    if(isdigit(m_my.GetAt(i)))
    {
          temp.SetAt(j,m_my.GetAt(i));  //it krashes here
          ++j;
    }
}

---

why can´t i use SetAt? i have tryed different ways to get it to work, like temp[j]=m_my.GetAt(i), but i get errors...

regards /Anne