Array of char of C++ [duplicate]

I have working code of int array and I try to do exactly the same code but with char. Something goes wrong, I got some huge amount of symbols instead.

char size_ch_array; // Something crazy here!!!!!!!!!!!!!!!!!!!
    cout << "Give me you size of Char Array" << endl;
    cin >> input_ch_size1;
    cin >> input_ch_size2;

    char rand_ch_array [input_ch_size1] [input_ch_size2];
            for (char m=0; m<input_ch_size1; m++)
                for (char n=0; n<input_ch_size2; n++)
                rand_ch_array [m] [n] = rand()%2;

            cout << "Your crazy array" << endl;
                for (char m=0; m<input_size1; m++)
                    for (char n=0; n<input_size2; n++)
            cout << rand_ch_array [m] [n] << " " << flush;
        cout << endl; 

I want to do func rand()%26 // where 26 letters of abc. I want to see the array of my size from 'a' to 'f', of different 26 letters or less?