Implement strStr().
Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.
Update (2014-11-02):
The signature of the function had been updated to return the index instead of the pointer. If you still see your function signature returns a char * or String, please click the reload button to reset your code definition.
1 int strStr(string haystack, string needle) { 2 int i=0,j=0,k=0; 3 int lenh=haystack.length(); 4 int lenn=needle.length(); 5 if(lenn>lenh) 6 return -1; 7 if(lenn==0) 8 return 0; 9 for(i=0;i<lenh-lenn+1;i++) 10 { 11 j=0;k=i; 12 while(haystack[k]==needle[j]) 13 { 14 if(j==lenn-1) 15 return k-j; 16 j++; 17 k++; 18 } 19 20 } 21 22 return -1; 23 }
原文：http://www.cnblogs.com/hexhxy/p/4817858.html