Question

我想在代码中动态使用Tuple，并且必须将值 according 分配给if语句。我有以下代码：

if(check != null)
  var scoreTmpTuple = new Tuple<Guid, string, double>(
    (Guid)row["sampleGuid"],
     Convert.ToString(row["sampleName"]), 
     Convert.ToDouble(row["sampleScore"]));
else
  var scoreTmpTuple = new Tuple<Guid, string, double>(
    (Guid)row["exampleGuid"],
     Convert.ToString(row["exampleName"]), 
     Convert.ToDouble(row["exampleScore"]));

在代码中，元组在if和else语句的内部中声明。我想声明 outside 并相应地初始化元组。

Answer 1

只需显式指定类型，而不使用var：

Tuple<Guid, string, double> scoreTmpTuple;

if (check != null)
    scoreTmpTuple = Tuple.Create<Guid, string, double>(Guid.NewGuid(), "hello", 3.14);

Answer 2

在if语句之前声明元组。

Tuple<Guid, string, double> scoreTmpTuple;

if(check != null)
   scoreTmpTuple = new Tuple<Guid, string, double>((Guid)row["sampleGuid"],Convert.ToString(row["sampleName"]), Convert.ToDouble(row["sampleScore"]));

else
   scoreTmpTuple = new Tuple<Guid, string, double>((Guid)row["exampleGuid"],Convert.ToString(row["exampleName"]), Convert.ToDouble(row["exampleScore"]));

Answer 3

您可以尝试三元运算符并在元组创建过程中推送分支：

  var scoreTmpTuple = Tuple.Create(
                (Guid)row[check != null ? "sampleGuid" : "exampleGuid"],
     Convert.ToString(row[check != null ? "sampleName" : "exampleName"]),
     Convert.ToDouble(row[check != null ? "sampleScore" : "exampleScore"])
  );

甚至（如果我们实际上应该在"sample"和"example"前缀之间切换）：

  string prefix = check != null 
    ? "sample"
    : "example";

  var scoreTmpTuple = Tuple.Create(
                (Guid)row[$"{prefix}Guid"],
     Convert.ToString(row[$"{prefix}Name"]),
     Convert.ToDouble(row[$"{prefix}Score"])
  );

Answer 4

您可以这样做：

bool isChecked = check != null;

var scoreTmpTuple = new Tuple<Guid, string, double>(
                      isChecked ? (Guid)row["sampleGuid"] : (Guid)row["exampleGuid"],
                      isChecked ? Convert.ToString(row["sampleName"]) : Convert.ToString(row["exampleName"]), 
                      isChecked ? Convert.ToDouble(row["sampleScore"]) : Convert.ToDouble(row["exampleScore"]));

在不初始化C＃的情况下声明元组

4 个答案: