void strToUpper(string &line)
{
for (int i = 0; i < line.length(); i++)
    if (islower(line[i]))
        toupper(line[i]);
}
void strToLower(string &line)
{
for (int i = 0; i < line.length(); i++)
    if (isupper(line[i]))
        tolower(line[i]);
}
void main()
{
int selecter;
string line;
cout << "Enter line:";
getline(cin, line);
cout << "Select (1-upper, 2-lower)n";
cin >> selecter;
if (selecter == 1)
   strToUpper(line);
else if (selecter == 2)
    strToLower(line);
else
{
    cout << "ERROR!";
    return;
}
cout << line << "nnnn";
}