c - Recursive method for palindrome checkup -

is possible define recursive method palindrome checkup following argument list?

int testpalindromerecursive(char* str, int len) { ... } 

note: no external sub-functions or global variables have used

i think impossible, because have remember last (front) index position somehow.

yes, possible - several people have mentioned.

base cases:

• if len <= 1, return true
• if str[0] != str[len-1] return false

else: recurse (str+1, len -2)