Is it critical to release variable memory in a function?

[soroush_vs]

Hello,
suppose we declared and initialized two variable in a function like this:

int function test()
{
CString str;
int index;
str="this is a test";
i=0;
//other statements to manipulate these variables
return TRUE;
}

Now suppose we call this function from main function.Am I must release the memory allocated by str and index variables or they will be released automatically after termination of the function?
if the application ended, memories that allocated by these 2 variables will release automatically or I have to release them manually?
Please consider that one of them (str) is a Class and another (index) is a base variable.
Thanks alot !