C++ while循环中的if/else格式 while（true） { 您必须将语句括在括号内的if和else之间{..}

您需要在此处添加括号：

while(true)
{ 
  cout << "Name: ";
  getline(cin, Name);
  if(Name == "Stop")
    break;

  cout << "Additional Name - Y/N: ";
  getline(cin, additional);
  if (additional == "Y") 
    cout << "Additional Name: ";
  getline(cin, Name2);
  else
    cout << "Location: ";
  getline(cin, Location);
  if(Location == "Stop")
    break;
}


chief.cpp: In member function ‘void BookList::Fill()’:
chief.cpp:128: error: ‘else’ without a previous ‘if’

if（附加==“Y”）
cout您需要将
if
主体括在大括号中以消除错误。从外观上看，您还需要将
else
主体括在大括号中：

if (additional == "Y") 
{
     cout << "Additional Name: ";
     getline(cin, Name2);
}
// You could have an else here, but that would make location only happen if "additional" was not "Y"

 cout << "Location: ";
 getline(cin, Location);

if（附加==“Y”）{
cout当块正好包含一条语句（以分号（
；
）结尾的语句）或另一条带块的语句（
if
，
for
，
while
等）时，只能丢弃块周围的大括号（
{
和
}
）

例如，您可以执行以下操作：

if (additional == "Y") {
  cout << "Additional Name: ";
  getline(cin, Name2);
 } else {
  cout << "Location: ";
  getline(cin, Location);
 }

甚至

while (true)
    if (foo) {
        printf("Hello, ");
        printf("world\n");
    }

如果您在清单上指明了第128行，这将非常有用，尽管您确实得到了有用的答案。
while (true)
    if (foo) {
        printf("Hello, ");
        printf("world\n");
    }

while (true)
    if (foo)
        for (i = 0; i < 10; i++) {
            printf("Hello, ");
            printf("World!\n");
        }

if (additional == "Y") {
   cout << "Additional Name: ";
   getline(cin, Name2);
}
else {
   cout << "Location: ";
   getline(cin, Location);
}