c# - 如何在程序中进一步使用switch语句内分配的变量？

Question

我正在尝试根据当前场景的索引（在Unity术语中）读取不同的文本文件。因此，我决定使用如下switch语句：

void MyReadString()
{
    Scene currentScene = SceneManager.GetActiveScene(); // Unity command to get the current scene info
    int buildIndex = currentScene.buildIndex; // Unity command to get the current scene number
    string path = string.Empty; // Create an empty string variable to hold the path information of text files
    switch (buildIndex)
    {
        case 0:
            string path = "Assets/Scripts/some.txt"; //It says here that the variable path is assigned but never used!
            break;
        case 1:
            string path = "Assets/Scripts/another.txt"; //Same here - assigned but never used. 
            break;
        // and many other cases - atleast 6 more
    } 
    StreamReader reader = new StreamReader(path); // To read the text file
    // And further string operations here - such as using a delimiter, finding the number of values in the text etc
}

如果我将这一行注释掉：

string path = string.Empty;

然后，

StreamReader reader = new StreamReader(path); // says here the name "path" does not exist in the current context.

我知道这与switch语句的范围有关。但是，将开关外部的字符串变量声明为“空”是行不通的。请让我知道是否可以在Switch语句中分配字符串值并稍后使用该值。或者，如果不可能，请向我建议解决方法。

Answer 1

您遇到问题是因为您在switch语句中再次重新声明了path变量。仅在switch语句外部声明一次，然后在switch语句中对其进行分配。

void MyReadString()
{
    Scene currentScene = SceneManager.GetActiveScene(); // Unity command to get the current scene info
    int buildIndex = currentScene.buildIndex; // Unity command to get the current scene number
    string path = null;
    // Create an empty string variable to hold the path information of text files
    switch (buildIndex)
    {
        case 0:
            path = "Assets/Scripts/some.txt"; //It says here that the variable path is assigned but never used!
            break;
        case 1:
            path = "Assets/Scripts/another.txt"; //Same here - assigned but never used. 
            break;
            // and many other cases - atleast 6 more
    }
    StreamReader reader = new StreamReader(path); // To read the text file                                               // And further string operations here - such as using a delimiter, finding the number of values in the text etc
}

无关，但请注意，这不是在Unity中读取文件的方式。构建项目时，该代码将失败。使用Resources API或使用Assetbundles。