本文整理汇总了C#中System.Linq.Expressions.Expression.Block方法的典型用法代码示例。如果您正苦于以下问题：C# Expression.Block方法的具体用法？C# Expression.Block怎么用？C# Expression.Block使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类System.Linq.Expressions.Expression的用法示例。
在下文中一共展示了Expression.Block方法的2个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C#代码示例。
示例1:
// Add the following directive to your file:
// using System.Linq.Expressions;
// This block has a parameter expression
// that represents a variable within the block scope.
// It assigns a value to the variable,
// and then adds a constant to the assigned value.
ParameterExpression varExpr = Expression.Variable(typeof(int), "sampleVar");
BlockExpression blockExpr = Expression.Block(
new ParameterExpression[] { varExpr },
Expression.Assign(varExpr, Expression.Constant(1)),
Expression.Add(varExpr, Expression.Constant(5))
);
// Print out the expressions from the block expression.
Console.WriteLine("The expressions from the block expression:");
foreach (var expr in blockExpr.Expressions)
Console.WriteLine(expr.ToString());
Console.WriteLine("The result of executing the expression tree:");
// The following statement first creates an expression tree,
// then compiles it, and then executes it.
Console.WriteLine(
Expression.Lambda<Func<int>>(blockExpr).Compile()());输出：
The expressions from the block expression: (sampleVar = 1) (sampleVar + 5) The result of executing the expression tree: 6
示例2: typeof
// Add the following directive to your file:
// using System.Linq.Expressions;
// The block expression allows for executing several expressions sequentually.
// When the block expression is executed,
// it returns the value of the last expression in the sequence.
BlockExpression blockExpr = Expression.Block(
Expression.Call(
null,
typeof(Console).GetMethod("Write", new Type[] { typeof(String) }),
Expression.Constant("Hello ")
),
Expression.Call(
null,
typeof(Console).GetMethod("WriteLine", new Type[] { typeof(String) }),
Expression.Constant("World!")
),
Expression.Constant(42)
);
Console.WriteLine("The result of executing the expression tree:");
// The following statement first creates an expression tree,
// then compiles it, and then executes it.
var result = Expression.Lambda<Func<int>>(blockExpr).Compile()();
// Print out the expressions from the block expression.
Console.WriteLine("The expressions from the block expression:");
foreach (var expr in blockExpr.Expressions)
Console.WriteLine(expr.ToString());
// Print out the result of the tree execution.
Console.WriteLine("The return value of the block expression:");
Console.WriteLine(result);输出：
The result of executing the expression tree:
Hello World!
The expressions from the block expression:
Write("Hello ")
WriteLine("World!")
42
The return value of the block expression:
42