Uppercase percent per line from file

#include <iostream>
#include <fstream>
using namespace std;

int uppercase_in_text(string testo) {
    int uppercase_counter = 0;

    for (char carattere_testo : testo){
        if (isupper(carattere_testo)){
            uppercase_counter++;
        }
    }

    return uppercase_counter;
}


int main(){
    int sum_uppercase = 0, char_in_file = 0;
    ifstream file1{"input_9.1.txt"};

    for (string line; getline(file1, line);){
        char_in_file += sizeof(line);
        int upper_in_line = uppercase_in_text(line);
        sum_uppercase += upper_in_line;
        cout << "Uppercase percent for this line: " << float(upper_in_line) / sizeof(line) * 100 << "%" << endl;
    }
    cout << "Uppercase percent for the whole text: " << float(sum_uppercase) / char_in_file * 100 << "%" << endl;
}