当用户输入非整数或数字的内容时，如何允许用户再次重新输入音乐选择。我在代码中使用isdigit。谢谢
我尝试使用isalpha来检测用户何时输入字母。但这也不起作用。我也尝试使用while（x <1 || x> 18）;太。我正在使用箭头键（上下）作为菜单输入。所以这里的代码有点长
class Music
{
private:
int song; //song selection
public:
void Song_Name() //function for song selection
{
do
{
cout<<" These are the music available: "<<endl<<endl;
cout<<" 1. American Teen (Khalid) "<<endl;
cout<<" 2. All We Know (Chainsmokers) "<<endl;
cout<<" 3. Born To Be Yours (Kygo) "<<endl;
cout<<" 4. Bodak Yellow (Cardi-B) "<<endl;
cout<<" 5. Beach House (Chainsmokers) "<<endl;
cout<<" 6. Congratulations (Post Malone) "<<endl;
cout<<" 7. Coaster (Khalid) "<<endl;
cout<<" 8. Danger (Migos & Marshmello) "<<endl;
cout<<" 9. Earth (Lil Dicky) "<<endl;
cout<<" 10. Eastside (benny blanco, Halsey, Khalid) "<<endl;
cout<<" 11. Happier (Marhsmello) "<<endl;
cout<<" 12. Heaven (Avicii) "<<endl;
cout<<" 13. Heaven (Khalid) "<<endl;
cout<<" 14. Here With Me (Marshmello) "<<endl;
cout<<" 15. Joy (Bastille) "<<endl;
cout<<" 16. lovely (Khalid & Billie Eilish) "<<endl;
cout<<" 17. I Fall Apart (Post Malone) "<<endl;
cout<<" 18. I Don't Belong In This Club (Why Don't We) "<<endl;
cout<<endl<<endl;
cout<<"Please enter the songs that you would like to listen: ";
cin>>song;
if(isdigit(song)==0) //check for alphabet input
{
cout<<"Invalid Input! Please Enter Digits Only "<<endl;
system("pause");
system("cls");
}
}while(isdigit(song)==0); //repeat again if alphabet is inputted
}
};
while(running)
{
system("pause>nul"); // the >nul bit causes it the print no message
if(GetAsyncKeyState(VK_DOWN) && a != 11) //down button pressed
{
if(a==-1)
{
gotoXY(75,4); cout << "Main Menu";
gotoXY(100,5); cout<< endl << " .................................. "<<endl;
gotoXY(100,6); cout<< endl << " : .............................. : "<<endl;
gotoXY(100,7); cout<< endl << " : : : : "<<endl;
gotoXY(100,8); cout<< endl << " : : 1) Sort By Song's Name : : "<<endl;
gotoXY(100,9); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,10); cout<< endl << " : : : : "<<endl;
gotoXY(100,11); cout<< endl << " : : 2) Sort By Genres : : "<<endl;
gotoXY(100,12); cout<< endl << " : : : : "<<endl;
gotoXY(100,13); cout<< endl << " : : : : "<<endl;
gotoXY(100,14); cout<< endl << " : : 3) Favourites List : : "<<endl;
gotoXY(100,15); cout<< endl << " : : : : "<<endl;
gotoXY(100,16); cout<< endl << " : : : : "<<endl;
gotoXY(100,17); cout<< endl << " : : 4) Exit Program : : "<<endl;
gotoXY(100,18); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,19); cout<< endl << " :................................: "<<endl;
a=0;
menu_item=0;
continue;
}
if(a==0)
{
gotoXY(75,4); cout << "Main Menu";
gotoXY(100,5); cout<< endl << " .................................. "<<endl;
gotoXY(100,6); cout<< endl << " : .............................. : "<<endl;
gotoXY(100,7); cout<< endl << " : : : : "<<endl;
gotoXY(100,8); cout<< endl << " : : 1) Sort By Song's Name : : "<<endl;
gotoXY(100,9); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,10); cout<< endl << " : : : : "<<endl;
gotoXY(100,11); cout<< endl << " : : 2) Sort By Genres : : "<<endl;
gotoXY(100,12); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,13); cout<< endl << " : : : : "<<endl;
gotoXY(100,14); cout<< endl << " : : 3) Favourites List : : "<<endl;
gotoXY(100,15); cout<< endl << " : : : : "<<endl;
gotoXY(100,16); cout<< endl << " : : : : "<<endl;
gotoXY(100,17); cout<< endl << " : : 4) Exit Program : : "<<endl;
gotoXY(100,18); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,19); cout<< endl << " :................................: "<<endl;
a=1;
menu_item=1;
continue;
}
if(a==1)
{
gotoXY(75,4); cout << "Main Menu";
gotoXY(100,5); cout<< endl << " .................................. "<<endl;
gotoXY(100,6); cout<< endl << " : .............................. : "<<endl;
gotoXY(100,7); cout<< endl << " : : : : "<<endl;
gotoXY(100,8); cout<< endl << " : : 1) Sort By Song's Name : : "<<endl;
gotoXY(100,9); cout<< endl << " : : : : "<<endl;
gotoXY(100,10); cout<< endl << " : : : : "<<endl;
gotoXY(100,11); cout<< endl << " : : 2) Sort By Genres : : "<<endl;
gotoXY(100,12); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,13); cout<< endl << " : : : : "<<endl;
gotoXY(100,14); cout<< endl << " : : 3) Favourites List : : "<<endl;
gotoXY(100,15); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,16); cout<< endl << " : : : : "<<endl;
gotoXY(100,17); cout<< endl << " : : 4) Exit Program : : "<<endl;
gotoXY(100,18); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,19); cout<< endl << " :................................: "<<endl;
a=2;
menu_item=2;
continue;
}
if(a==2)
{
gotoXY(75,4); cout << "Main Menu";
gotoXY(100,5); cout<< endl << " .................................. "<<endl;
gotoXY(100,6); cout<< endl << " : .............................. : "<<endl;
gotoXY(100,7); cout<< endl << " : : : : "<<endl;
gotoXY(100,8); cout<< endl << " : : 1) Sort By Song's Name : : "<<endl;
gotoXY(100,9); cout<< endl << " : : : : "<<endl;
gotoXY(100,10); cout<< endl << " : : : : "<<endl;
gotoXY(100,11); cout<< endl << " : : 2) Sort By Genres : : "<<endl;
gotoXY(100,12); cout<< endl << " : : : : "<<endl;
gotoXY(100,13); cout<< endl << " : : : : "<<endl;
gotoXY(100,14); cout<< endl << " : : 3) Favourites List : : "<<endl;
gotoXY(100,15); cout<< endl << " : : : : "<<endl;
gotoXY(100,16); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,17); cout<< endl << " : : 4) Exit Program : : "<<endl;
gotoXY(100,18); cout<< endl << " : :............................: : "<<endl;
gotoXY(100,19); cout<< endl << " :................................: "<<endl;
a=3;
menu_item=3;
continue;
}
if(a==3)
{
a=-1;
continue;
}
}
答案 0 :(得分：0)
在成员函数Song_Name中，您要检查条件两次。尝试这样。
void Song_Name()
{
do
{
cin << song;
if (song >= 1 && song <= 18) break;
else
{
// pause and clear
}
} while (true);
}
while (running)下的代码重复太多，请尝试
void printMessage()
{
/*
gotoXY(75,4); cout << "Main Menu";
gotoXY(100,5); cout << endl << ".................................. " << endl;
etc
*/
}
和
while (running)
{
switch (a) {
case -1:
printMessage();
a = 0;
menu_item = 0;
break;
case 0:
printMessage();
a = 1;
menu_item = 1;
break;
}
}