c++ - I'm trying to create a function that toggles between a 24 hour clock and a 12 hour clock using Boolean expressions -

in program creating, need able toggle option main menu change 24 hour clock 12 hour clock , vice versa. understand need swap bool values in order create toggle, have no idea how so. here function below:

void printtime(int h, int m, bool mode) { if (mode = 0) {     mode = 1;     cout << "24-hour mode turned on" << endl; } else {     mode = 0;     cout << "12-hour mode turned on" << endl; } } 

to able change variable outside function's scope should pass reference.

void printtime(int h, int m, bool& mode) {     mode = !mode; //toggle mode     std::cout << (mode ? "24" : "12") << "-hour mode turned on" << std::endl; } 

then can change value in different scope;

int main() {     bool mode24 = true;     printtime(2, 4, mode24); //changes mode24 false     printtime(2, 4, mode24); //changes mode24 true      return 0; }