I want to declare a data type of char*, but I do not know the # of characters I will be needed. Is there anyway to increase the size of such variable as I go along? (e.g. when i run out of space)

I can't work around by doing this:
char* a = new char [myInt];
because by the time of declaring this statement, I still dont know the size of the char*. btw, I need to use char* data type.

any advises?