c# - 为什么此 C# 代码会引发错误 : Use of unassigned local variable 'n'

Question

在 MSDN 上，此代码发布在 https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/try-catch我无法理解为什么会抛出错误:

Use of unassigned local variable 'n'.

static void Main()   
{  
    int n;  

    try   
    {  
        // Do not initialize this variable here.  
        n = 123;  
    }  
    catch  
    {  
    }  

    // Error: Use of unassigned local variable 'n'.  
    Console.Write(n);  
}

Answer 1

Compiler Error CS0165

The C# compiler does not allow the use of uninitialized variables. If the compiler detects the use of a variable that might not have been initialized, it generates compiler error CS0165. For more information, see Fields. Note that this error is generated when the compiler encounters a construct that might result in the use of an unassigned variable, even if your particular code does not. This avoids the necessity of overly-complex rules for definite assignment.

更是如此，想象一下这种情况

int n;  

try   
{  
    throw new Exception();
    n = 123;  // this code is never reached
}  
catch  
{  
}  

// oh noez!!! bam!
// The compiler is trying to be nice to you 
if(n == 234);

简而言之，电脑说不

注意:当您在 visual studio 中遇到编译器错误时，您可以单击错误代码，它有时(如果您幸运的话)会为您提供有关错误含义的更简洁的信息