read greek letters from a file c++

Question

I have this which reads line by line from a file:

 try{
    streampos begin,end;        
    char delimeter[3] = {',', '\n', '\0'};
    int numChars = 0, tmpNumChars = 0;
    int pos1 = 0, pos2 = 0, pos3 = 0, startIndex = 0;
    ifstream file1("Students.txt", ios::in);
    if (!file1) throw MyExceptions();
    begin = file1.tellg();
    file1.seekg (0, ios::end);
    end = file1.tellg();
    int size =  end - begin;
    file1.seekg(0, ios::beg);      
    char charField[size];        

    while(file1.getline(charField, size, '\n'))
    { 
        char *tmpCharField1 = charField;                        
        while(*tmpCharField1 != '\0'){
            numChars++;
            tmpCharField1++;
        }            
        tmpNumChars = numChars;            
        while(tmpNumChars > 0){
            tmpCharField1--;
            tmpNumChars--;
        }         

        CustomString tmpStudent(tmpCharField1, numChars);
        pos1 = tmpStudent.findCharacter(&delimeter[0], startIndex);
        CustomString tmpStudentCode = tmpStudent.subString(startIndex, pos1);
        pos2 = tmpStudent.findCharacter(&delimeter[0], (pos1 + 1));
        CustomString tmpFirstName = tmpStudent.subString((pos1 + 1), pos2);
        pos3 = tmpStudent.findCharacter(&delimeter[2], (pos2 + 1));
        CustomString tmpSecondName = tmpStudent.subString((pos2 + 1), pos3);
        Student student(tmpStudentCode, tmpFirstName, tmpSecondName);
        this->StudentVector.push_back(student);
        numChars = 0;
    }        
    file1.close();
}

It runs perfectly but I do not know how to read a file with Greek Letters:

ΔΔΔΔ1,ΔΔΔΔ2,ΔΔΔΔ3
ΔΔΔΔ4,ΔΔΔΔ5,ΔΔΔΔ6
ΔΔΔΔ7,ΔΔΔΔ8,ΔΔΔΔ9

The above is an example with the format of the file, but I have to read First Names, Second Names in Greek. Any suggestion?