read file, analyse characters

Hi community.
In my current project I have to read a file and count the occurences of characters. Normal characters work fine ( like a-z), but I also need to analyse some special chars like ü,ä,ö.

I began like this:

int currentchar;
vector<int> ascii(256, 0);

textfile.open("text.txt");
    while(textfile >> line) {
        lastpos = line.size()-1;
        cout<<line<<endl; //displays the line in console codepage
        for(i = 0; i <= lastpos; i++) {
            //this should convert one character to its index on codepage
            currentchar = line[i];
            //this counts the characters
            ascii[currentchar]++;
        }

    }
textfile.close();

I saved it in Windows-Editor ("ANSI"-Encoding).
When the algorithm analyses for example a line containing "ü", it displays the line in the right way (the "ü" is replaced by "³", cause this is index 252 in console-codepage). But when it comes to convert "³" to integer (the index) than i get huge numbers like 426...
What can I do to get 252 as it stands for "³" in console and for "ü" in windows?

mfg rider

correction:

I saved the "text.txt" in ANSI-Encoding. (not "it").