How do I limit the amount of digits accepted from the user? - c++

Question

I currently have this and I can't seem to make my else work so the whole program doesn't limit the input successfully. (Sorry for my English I speak French).
cout << "Veuillez entrer votre nombre de 6 chiffres : ";
cin >> val;
if (val < 100000);
{
cout << "Erreur! Veuillez recommencez avec un nombre a 6 chiffres. " << endl << endl;
return main();
}
if (val > 999999);
{
cout << "Erreur! Veuillez recommencez avec un nombre a 6 chiffres. " << endl << endl;
return main();
}
else
if
{
nb1 = val / 100000 % 10;
cout << nb1;
}

Answer 1

Firstly, a semicolon between the ) and { of an if statement creates an empty if statement body, followed by an unconditional block, which is not what you want.
To check if a number has more than a certain number of digits, try comparing against negative 999999 instead.
The code should be made shorter by using logical operators instead of 2 separate if statements.
Lastly, you should not recurse into main(). Use goto instead.
Corrected Code:
retry:
cout << "Veuillez entrer votre nombre de 6 chiffres : ";
cin >> val;
if (val < -999999 || val > 999999) // Note the ; has been removed
{
cout << "Erreur! Veuillez recommencez avec un nombre a 6 chiffres. " << endl << endl;
goto retry;
}
nb1 = val / 100000 % 10;
cout << nb1;
Alternatively, you could use the abs() function (use #include <cstdlib>):
if (abs(val) > 999999)
{
cout << "Erreur! Veuillez recommencez avec un nombre a 6 chiffres. " << endl << endl;
goto retry:
}
nb1 = val / 100000 % 10;
cout << nb1;