I don't know if there is any stl hash_map. U need to use just map instead, with a #include <map>

The map as a whole can not displayed using cout. Try

Of course, if you put the delete statement after the return statement, it won't be executed at all. Instead you can do like

If you are afraid of delete, using auto_ptr can be a good option.

The problem is that when your function is returning a string, it first makes a copy of the string to be returned (in your case, it is NULL). For making copy, it has to take the length of the original...

The problem seems to be in

while(isalpha(ch))
{
text[i] = ch;
i++;
}

If the first character is an alphabet, it will go on filling the array text with that...

only the first example invokes copy constructor. If the second one needs to work in the same manner as copy constructor does, you have to overload the assignment operator.

[] operator is the best to add values to an array, I think. Applicable only if you know the index in advance.
If you have to search in runtime for the position to which we can add a value, it will...

I wonder when the loop while (*a++ = *temp++) will end. Also, as you have done an a++, the beginning of the string is altered.
I suggest using the following code.
int i = 0;
while (i <...