Reading n characters at a time

[ochoaj]

So i have a file that has the following:

ABCDE
LMNOP

and i want to read 3 characters at a time. So for example i want to output:
ABC
BCD
CDE
DEL
ELM
LMN
...

// Helper function to get a k-mer (it ignores newline characters)
void read(std::ifstream & in, std::string & string, int streamsize){
        int pos=0;
        // Read streamsize number of characters from stream discarting 
        // newline characters
        while(pos<streamsize){
                in >> string[pos];
                ++pos;
        }
}


 void read_file(char * file, int kmer){
        // open file
        std::ifstream input( file );
        // check that file if okay for operations
        assert(input.good());

        // Current string(character) being read from file
        std::string cursor;
        cursor.resize( kmer );

        // Position in stream
        int charPos=1;
        // Read file
        while( !input.eof() ){
                // Get a kmer from the file stream
                read( input, cursor, kmer );

                // If stream has not ended
                if (!input.eof()){
                        std::cout<< cursor <<'\n';
                } 
                else { break; }

                // Save place in stream
                input.seekg( charPos++ );
        }

        // Close file
        input.close();
}

But this outputs:
ABC
BCD
CDE
DEL
ELM
LMN
LMN
MNO
NOP

The problem is that I don't know how to avoid the function seekg step back but avoid newline chaaracters. Does anyone know how to overcome this?

[ochoaj]

After you go back in the stream check if the next thing in the stream is a newline character by adding:

'if (input.peek() == '\n') ++charPos;'