c++ string split

vector<string> split(const string& str, const string& delim) {  
    vector<string> res;  
    if("" == str) return res;  
    //先将要切割的字符串从string类型转换为char*类型  
    char * strs = new char[str.length() + 1] ; //不要忘了  
    strcpy(strs, str.c_str());   
 
    char * d = new char[delim.length() + 1];  
    strcpy(d, delim.c_str());  
 
    char *p = strtok(strs, d);  
    while(p) {  
        string s = p; //分割得到的字符串转换为string类型  
        res.push_back(s); //存入结果数组  
        p = strtok(NULL, d);  
    }  
 
    return res;  
}