Counting characters in a program C++ NEED ASSISTANCE

[Sxc]

I am wondering what syntax to use in order to count how many characters there are in my .txt file. In my .txt file is the alphabet (ABCDEFGHIJKLMNOPQRSTUVWXYZ), and that is all.

Here is what I have so far:

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main()
{

string letters = "";



ifstream inFile;
inFile.open("Intermediate21.txt");

if(inFile.is_open())
{
getline(inFile, letters);

cout << letters << endl;

inFile.close();
}
else
cout << "cannot open file." << endl;


system("pause");
return 0;

}



So I am able to display the .txt file but I also have to cout the amount of characters there are also (26).


Thanks.

[vlad from moscow]

I suppose that you mean alpha characters. Otherwise you can use member function size() to determine how many characters the string contains. If so than you should use isalpha function. For example

int count = std::count_if( letters.begin(), letters.end(),
                                      [] ( char c ) { return ( std::isalpha( c ) ); } );

[Sxc]

And where would I put that :o

inside of the if(inFile.is_open()) statement?

[vlad from moscow]

if(inFile.is_open())
 {
 getline(inFile, letters);

 cout << letters << endl;
 
cout << std::count_if( letters.begin(), letters.end(),
                                  [] ( char c ) { return ( std::isalpha( c ) ); } )
       << endl;

 inFile.close();
 }

[Sxc]

Okay.. and then do I need to replace anything inside the [] or anything because it won't compile lol

I get:

expected primary-expression before '[' token
expected primary-expression before ']' token
expected primary-expression before "char"

[vlad from moscow]

It seems that your compiler does not support the new C++ Standard that is lambda expressions.
You can change the lambda expression to a functional object.

struct count_alpha: std::unary_function<char, bool>
{
   bool operator ()( char c ) const
   {
      return ( std::isalpha( c ) );
   }
};

//....

std::cout << std::count_if( letters.begin(), letters.end(), count_alpha() ) 
              << std::endl;

[Cubbi]

It's really sufficient to just call isalpha directly, with a disambiguating cast:

std::count_if( letters.begin(), letters.end(), (int(*)(int))std::isalpha )

unless you're being excessively pedantic and coding for the imaginary standards-compliant implementation where <cctype>'s std::isalpha takes defaulted arguments past the int.

Also, the above samples count the letters per line. To count the entire file, iterate over the entire file:

#include <fstream>
#include <cctype>
#include <iostream>
#include <iterator>
#include <algorithm>

int main()
{
    std::ifstream inFile("Intermediate21.txt");
    std::cout << std::count_if( std::istreambuf_iterator<char>(inFile),
                                std::istreambuf_iterator<char>(),
                                (int(*)(int))std::isalpha ) << '\n';
}