Question

为什么在下面的示例中第一个（x）为真，第二个（y）为假？我想在C＃中使用类似VB的运算符。

Dim x = "abc@symas-design.ch" Like "*symas-design.ch"
Dim y = Microsoft.VisualBasic.CompilerServices.Operators.LikeString("abc@symas-design.ch", "*symas-design.ch", CompareMethod.Text)

Answer 1

Like运算符显然不使用Operators.LikeString，而是使用LikeOperator.LikeString。

我尝试了这个LINQPad计划：

Sub Main
    Dim x = "abc@symas-design.ch" Like "*symas-design.ch"
    Dim y = Microsoft.VisualBasic.CompilerServices.Operators.LikeString("abc@symas-design.ch", "*symas-design.ch", Microsoft.VisualBasic.CompareMethod.Text)

    x.Dump()
    y.Dump()
End Sub

它显示：

True
False

正如你所说，他们不会这样做，但后来我展示了IL生成的：

IL_0000:  ldstr       "abc@symas-design.ch"
IL_0005:  ldstr       "*symas-design.ch"
IL_000A:  ldc.i4.0    
IL_000B:  call        Microsoft.VisualBasic.CompilerServices.LikeOperator.LikeString
IL_0010:  stloc.0     // x
IL_0011:  ldstr       "abc@symas-design.ch"
IL_0016:  ldstr       "*symas-design.ch"
IL_001B:  ldc.i4.1    
IL_001C:  call        Microsoft.VisualBasic.CompilerServices.Operators.LikeString
IL_0021:  stloc.1     // y
IL_0022:  ldloc.0     // x
IL_0023:  call        LINQPad.Extensions.Dump
IL_0028:  pop         
IL_0029:  ldloc.1     // y
IL_002A:  call        LINQPad.Extensions.Dump

似乎他们正在调用不同的方法，所以我尝试了这个：

Sub Main
    Dim x = "abc@symas-design.ch" Like "*symas-design.ch"
    Dim y = Microsoft.VisualBasic.CompilerServices.Operators.LikeString("abc@symas-design.ch", "*symas-design.ch", Microsoft.VisualBasic.CompareMethod.Text)
    Dim z = Microsoft.VisualBasic.CompilerServices.LikeOperator.LikeString("abc@symas-design.ch", "*symas-design.ch", Microsoft.VisualBasic.CompareMethod.Text)

    x.Dump()
    y.Dump()
    z.Dump()
End Sub

我得到了：

True   <-- Like operator
False  <-- Operator.LikeString
True   <-- LikeOperator.LikeString

因此您需要使用LikeOperator.LikeString。

这是一个C＃LINQPad程序，演示了：

void Main()
{
    bool z = LikeOperator.LikeString("abc@symas-design.ch", "*symas-design.ch", Microsoft.VisualBasic.CompareMethod.Text);
    z.Dump();
}

其中也输出True。

VB Like运算符与Operators.LikeString（）不同

1 个答案: