CODEWITHSUNDEEP
c++stringidioms
Aistis Taraskevicius
Aistis Taraskevicius

Reputation: 811

Removing non alphabetic character from string c++

This is driving me to the wall.

template<typename t>
void Tree<t>::readFromFile(string filename)
{
//
    str.erase( remove_if(str.begin(), str.end(), aZCheck), str.end());
//
}
template<typename t>
bool Tree<t>::aZCheck(char c)
{
    if (isalpha(c))
        return false;
    else return true;

}

Gives an error :cannot convert 'Tree<t>::aZCheck<std::basic_string<char> >' from type 'bool (Tree<std::basic_string<char> >::)(char)' to type 'bool (Tree<std::basic_string<char> >::*)(char)'|

Worked fine until I moved both methods into the class.

str.erase( remove_if(str.begin(), str.end(), isalpha), str.end());

Doesnt work without using static cast and I am using cctype or ctype.h libraries, static cast is for c++ locale library which I am not using.

I can get it to work using static cast, but then I cant seem to make it negative !isalpha. As I need to delete non alphabetic characters and as it is , it will delete alphabetic ones. Forcing me into creating separate method, which I mentioned as my first issue. And it worked until I moved method into class.

Chances are I am missing something completely obvious, but I just cant figure it out...

Upvotes: 1

Views: 2030

Answers (3)

Vlad from Moscow
Vlad from Moscow

Reputation: 311088

Declare the function as a static member function

static bool aZCheck(char c);

Take into account that the function could be defined simpler

template<typename t>
inline bool Tree<t>::aZCheck( char c )
{
    return isalpha( (unsigned char )c );

}

Upvotes: 3

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

You should provide a free function (outside of class declaration) or a static member function for aZCheck().

 template<typename t>
 class Tree {
 public:
     static bool aZCheck(char c);
 };

and use 

 str.erase( remove_if(str.begin(), str.end(), Tree<t>::aZCheck), str.end());

or better simply have a free function

 bool aZCheck(char c)  {
     return !isalpha(c));
 }

and use 

 str.erase( remove_if(str.begin(), str.end(), aZCheck), str.end());

Upvotes: 1

Dimitrios Bouzas
Dimitrios Bouzas

Reputation: 42929

If your compiler supports C++11 and thus lambdas you could just:

  str.erase(std::remove_if(str.begin(), str.end(), [](char c) { return !isalpha(c); }), str.end());

Upvotes: 2

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