Leetcode_Wildcard Matching

Implement wildcard pattern matching with support for '?' and '*'.

'?' Matches any single character.
'*' Matches any sequence of characters (including the empty sequence).

The matching should cover the entire input string (not partial).

The function prototype should be:
bool isMatch(const char *s, const char *p)

Some examples:
isMatch("aa","a") → false
isMatch("aa","aa") → true
isMatch("aaa","aa") → false
isMatch("aa", "*") → true
isMatch("aa", "a*") → true
isMatch("ab", "?*") → true
isMatch("aab", "c*a*b") → false
class Solution {
public:
    bool isMatch(const char *s, const char *p) {
       const char * ptr;
       const char *str;
       bool start = false;
       for(ptr=p,str=s; *str!=''  ; ){
           switch(*ptr){
               case '?':
               str++,ptr++;
               break;
               case '*':
               start = true;
               while(*ptr == '*')
                 ptr++;
               if(*ptr=='')
               return true;
               p = ptr;
               s = str;
               break;
               default:
               if(*ptr != *str){
                   if(!start)
                   return false;
                   ptr = p;
                   str = s+1;
                   s=s+1;
               }
              else{
                  ptr++;
                  str++;
              }
           }
       }
       while(*ptr=='*')  ptr++;
       
       return (*ptr == '');
    }
};