error C2440: 'initializing' : cannot convert from 'char *' to 'const class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > *'

error C2440: 'initializing' : cannot convert from 'char *' to 'const class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > *'

Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

//输出一行中所有字符  
void printchar(string &line)  
{  
    istringstream iss(line);  
    string word;  
    while(iss>>word)  
        for(vector<string>::const_iterator itbegin=word.begin(),itend=word.end();itbegin != itend; ++itbegin)  
            cout<<*itbegin<<endl;  
}

解决方法：标准库string对象可以使用迭代器操作 ，但是其迭代器要正确使用，应该使用string::const_iterator 后者使用下标操作来获取string对象中的字符。