if/else語句中的語法錯誤

Question

我對c＃非常陌生，並且在處理基本程序時收到此錯誤（錯誤只能將賦值，調用，遞增，遞減，等待和新對象表達式用作聲明），並無法弄清楚它出現的原因。

if (pizzaDiameter >= 12 && pizzaDiameter < 16)// begin nested if statement 
{ 
    Console.WriteLine("A" + pizzaDiameter + "will yield 8 slices."); 
} 
else if (pizzaDiameter >= 16 && pizzaDiameter < 24)//Second pizza diameter range 
{ 
    Console.WriteLine("A" + pizzaDiameter + "will yield 12 slices."); 
} 
else if (pizzaDiameter >= 24 && pizzaDiameter < 30) 
{ 
    Console.WriteLine("A" + pizzaDiameter + "will yield 16 slices."); 
} 
else (pizzaDiameter >= 24 && pizzaDiameter <= 30) 
{ 
    Console.WriteLine("A" + pizzaDiameter + "will yield 24 slices."); 
} 
else // pizza diameter was not a whole number 
{ 
    Console.WriteLine("Pizza diameter must be between 12-36 inclusive.");// Error appears here. 
} 
else //pizza diameter must be between 12-36 
{ 
    Console.WriteLine("Pizza diameter must be a whole number."); 
} 

Answer 1

有一些問題與您的控制結構，即你得只有一個if()，而是三次else。

另外，儘量去想問題，你會發現，你可以顯著簡化了整體結構（也跳過許多檢查）：

if (pizzaDiameter < 12) // All diameters below 12 will use this branch. 
    Console.WriteLine("Your pizza seems to be too small."); 
else if (pizzaDiameter < 16) // You don't have to ensure it's bigger than 12, since those smaller already picked the branch above. 
    Console.WriteLine("A diameter of " + pizzaDiameter + " will yield 8 slices"); 
else if (pizzaDiameter < 24) // Again you won't have to care for less than 16. 
    Console.WriteLine("A diameter of " + pizzaDiameter + " will yield 12 slices"); 
// ... 
else 
    Console.WriteLine("Your pizza seems to be too big.");