c++ - Using char as array index after using map -

i trying use character index array of integers after mapping it. problem whenever try access array using variable of type char(as array[char]), instead of using array["], getting error compiler. wonder if necessary use constant types after mapping. here code.

        int count=0;         int length=strlen(word);         std::map<std::string, int, std::less<std::string> >  alpha;         alpha["x"]=1;         alpha["y"]=2;         alpha["z"]=3;         char temp;         for(int i=0;i<length;i++)         {         temp=word[i];         count=alpha[temp];         } 

error(s) :

error: invalid user-defined conversion 'char' 'std::map, int, std::less > >::key_type&& {aka std::basic_string&&}' [-fpermissive] count=alpha[temp];

error: initializing argument 1 of 'std::basic_string<_chart, _traits, _alloc>::basic_string(const _chart*, const _alloc&) [with _chart = char; _traits = std::char_traits; _alloc = std::allocator]' [-fpermissive] basic_string(const _chart* __s, const _alloc& __a = _alloc());

there's no automatic conversion char std::string. have 2 options:

• make conversion explicit, count=alpha[std::string(1,temp)];
• change type of temp std::string. can assign char string, intuitive result, rest of code work

if all map keys single-character strings, might consider using char key; or using flat array large enough character value might need.