在c#中打印变量的名称
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print name of the variable in c#
提问by Anirudh Goel
i have a statement
我有一个声明
int A = 10,B=6,C=5;
and i want to write a print function such that i pass the int variable to it and it prints me the variable name and the value.
并且我想编写一个打印函数，以便我将 int 变量传递给它，它会向我打印变量名称和值。
eg if i call print(A) it must return "A: 10", and print (B) then it must return "B:6"
例如，如果我调用 print(A) 它必须返回“A: 10”，而 print (B) 那么它必须返回“B:6”
in short i want to know how can i access the name of the variable and print it to string in c#. DO i have to use reflection?
简而言之，我想知道如何访问变量的名称并将其打印为 C# 中的字符串。我必须使用反射吗？
After reading the answers
阅读答案后
Hi all, thanks for the suggestions provided. I shall try them out, however i wanted to know if it is at all possible in .NET 2.0? Nothing similar to
大家好，感谢提供的建议。我会尝试一下，但是我想知道在 .NET 2.0 中是否有可能？没有类似的
#define prt(x) std::cout << #x " = '" << x << "'" << std::endl;
macro which is there in C/C++?
C/C++ 中有哪些宏？
采纳答案by Marc Gravell
The only sensible way to do this would be to use the ExpressionAPI; but that changes the code yet further...
唯一明智的方法是使用ExpressionAPI；但这进一步改变了代码......
static void Main() {
int A = 10, B = 6, C = 5;
Print(() => A);
}
static void Print<T>(Expression<Func<T>> expression) {
Console.WriteLine("{0}={1}",
((MemberExpression)expression.Body).Member.Name,
expression.Compile()());
}
Note: if this is for debugging purposes, be sure to add [Conditional("DEBUG")]to the method, as using a variable in this way changes the nature of the code in subtle ways.
注意：如果这是出于调试目的，请务必添加[Conditional("DEBUG")]到方法中，因为以这种方式使用变量会以微妙的方式改变代码的性质。
回答by Brian
This is not possible without some 'help' from the call site; even reflection does not know about names of local variables.
如果没有呼叫站点的一些“帮助”，这是不可能的；甚至反射也不知道局部变量的名称。
回答by JaredPar
This is not possible to do with reflection (see Brian and Joel). In general this is not possible simply because you cannot guarantee a named value is being passed to your print function. For instance, I could just as easily do the following
这不可能与反射有关（参见 Brian 和 Joel）。一般来说，这是不可能的，因为您不能保证将命名值传递给您的打印函数。例如，我可以轻松地执行以下操作
print(42);
print(A + 42);
Neither of these expressions actually has a name. What would you expect to print here?
这些表达式实际上都没有名称。您希望在这里打印什么？
回答by TcKs
You can use lambda expressions:
您可以使用 lambda 表达式：
static void Main( string[] args ) {
int A = 50, B = 30, C = 17;
Print( () => A );
Print( () => B );
Print( () => C );
}
static void Print<T>( System.Linq.Expressions.Expression<Func<T>> input ) {
System.Linq.Expressions.LambdaExpression lambda = (System.Linq.Expressions.LambdaExpression)input;
System.Linq.Expressions.MemberExpression member = (System.Linq.Expressions.MemberExpression)lambda.Body;
var result = input.Compile()();
Console.WriteLine( "{0}: {1}", member.Member.Name, result );
}
回答by Igor Zevaka
Another solution (from a closed post):
另一个解决方案（来自封闭的帖子）：
Inspired by Jon Skeet's postabout Null Reference exception handling and suddenly being reminded about projection there is a way to kinda do that.
受 Jon Skeet关于 Null Reference 异常处理的帖子的启发，突然想起投影，有一种方法可以做到这一点。
Here is complete working codez:
这是完整的工作代码：
public static class ObjectExtensions {
public static string GetVariableName<T>(this T obj) {
System.Reflection.PropertyInfo[] objGetTypeGetProperties = obj.GetType().GetProperties();
if(objGetTypeGetProperties.Length == 1)
return objGetTypeGetProperties[0].Name;
else
throw new ArgumentException("object must contain one property");
}
}
class Program {
static void Main(string[] args) {
string strName = "sdsd";
Console.WriteLine(new {strName}.GetVariableName());
int intName = 2343;
Console.WriteLine(new { intName }.GetVariableName());
}
}
