C++ please and thank you

s is a txt file that contains integers. Why do I keep on getting 0 for the minimum value when I use the following code?

void minimum(string k) {

my_input_file.open(k);

while (my_input_file >> value) {

minimum = min(minimum, value);

my_input_file.close();

}

cout << "min " << minimum;

}

int main(){

string k =(" file.txt")

minimum(k)

}