Is there a proper way to close program from within function? - c++

Question

I am currently making a program that has menu and sub menus and i'd like to have an opportunity to close entire thing from within any sub menu (which is inside function). I know i could do it different way (both way i have it now and way i know it could be done are below) but for future use (i could prove useful) i would like to know:
Is there a way to properly close the program from within a function ?
I've read a few answers here and here and from what i've gotten out of it is:
I should not simply terminate the code
I should not use any system specific code as to avoid compatibilty issues
A bit of clarifiacation - that is program for my personal educational purposes so it is kind of unnecessary to worry about it but i'd rather learn propper ways of dealing with those situations at the beginning than have to learn them anew once i discover how to do them later and have to go back and fix it.
As for code samples (using visual studio 2017):
//skipping unrelevant to question bits of code
void sub_menu()
{
char a=0;
system("cls"); //yet to get changed when i'll find other way of clearing screen
std::cout << "Pick function:\n"
<< "---------------------------------------------------------\n"
<< "1.Foobar_1\n"
<<"---------------------------------------------------------\n"
<< "ESC to go back to menu menu\n"
<< "x to close";
while (a != 27)
{
a = _getch();
switch (a)
{
case 49:foobar_1(); break;
case 120:
case 88: system("exit"); break; //i'd like to replace that part
default: break;
};
};
return;
}
void main()
{
char a=0;
system("cls"); //yet to get changed when i'll find other way of clearing screen
std::cout << "Pick what you want to do:\n"
<< "---------------------------------------------------------\n"
<< "1.Sub_menu\n"
<< "2.foo\n"
<< "3.bar\n"
<<"---------------------------------------------------------\n"
<< "ESC to close\n"
while (a != 27)
{
a = _getch();
switch (a)
{
case 49:sub_menu(); break;
case 50:foo(); break;
case 51:bar(); break;
case 120:
case 88: system("exit"); break; //i'd like to replace that part
default: break;
};
};
return;
}
The way i could implement it (i think it is merely byapssing the issue):
//skipping unrelevant to question bits of code
void main()
{
char a=0;
system("cls"); //yet to get changed when i'll find other way of clearing screen
std::cout << "Pick what you want to do:\n"
<< "---------------------------------------------------------\n"
<< "1.Sub_menu\n"
<< "2.foo\n"
<< "3.bar\n"
<<"---------------------------------------------------------\n"
<< "ESC to close\n"
while (a != 27)
{
a = _getch();
switch (a)
{
case 49:
{
{
char b=0;
system("cls");
std::cout << "Pick function:\n"
<< "---------------------------------------------------------\n"
<< "1.Foobar_1\n"
<<"---------------------------------------------------------\n"
<< "ESC to go back to menu menu\n"
<< "x to close";
while (b != 27)
{
b = _getch();
switch (b)
{
case 49:foobar_1(); break;
case 120:
case 88: a=27; break;
default: break;
};
};
return;
}
}
; break;
case 50:foo(); break;
case 51:bar(); break;
case 120:
case 88: system("exit"); break; //i'd like to replace that part
default: break;
};
};
return;
}

Answer 1

This Code will work as you mentioned.
int main()
{
int a;
while (true)
{
system("cls"); //yet to get changed when i'll find other way of clearing screen
cout << "Pick what you want to do:\n"
<< "---------------------------------------------------------\n"
<< "1.Sub_menu\n"
<< "2.foo\n"
<< "3.bar\n"
<< "---------------------------------------------------------\n"
<< "0. to close\n";
cin >> a ;
if (a == 0)
{
return 0 ;
}
else if (a == 1)
{
char b;
while (true)
{
system("cls");
cout << "Pick function:\n"
<< "---------------------------------------------------------\n"
<< "1.Foobar_1\n"
<< "---------------------------------------------------------\n"
<< "b to go back to menu menu\n"
<< "x to close\n";
cin >> b;
if (b == '1')
{
foobar_1();
}
else if (b == 'B' || b == 'b')
{
break;
}
else if (b == 'x' || b == 'X')
{
return 0;
}
else
{
cout << "invalid input";
}
}
}
else if (a == 2)
{
foo();
}
else if (a == 3)
{
bar();
}
else
{
cout << "invalid input";
}
}
return 0;
}