Simple test lightweight expression calculator fly

  Flee yes GitHub Based on .net Lightweight mathematical expression parsing and calculator , It supports evaluating mathematical expressions 、 Mathematical expressions with variables 、 Mathematical expressions with special processing functions, etc . From the wechat official account, you can see about Flee The introduction of （ reference 1 It is a blog post of the same name from Baidu ）, Prepare to test , Use this module to calculate mathematical expressions and mathematical expressions with variables .
   Use VS2019 establish Winform Program , adopt NuGet Find and install Flee Packages and dependencies , As shown in the figure below ：


   Use Flee Calculating a mathematical expression without variables and special handling functions is simple , Just use the sample code given on its official website , The test code and running interface are shown in the following figure .

		try
        {
    
            ExpressionContext context = new ExpressionContext();
            IDynamicExpression calcResult = context.CompileDynamic(txtExpression.Text);
            txtResult.Text =Convert.ToString(calcResult.Evaluate());
        }
        catch (ExpressionCompileException ex)
        {
    
            if (ex.Reason == CompileExceptionReason.SyntaxError)
            {
    
                txtResult.Text = "Check your expression syntax" + "\r\n" + ex.Message;
            }
            else
            {
    
                txtResult.Text = ex.Message;
            }
        }

   Next, test the mathematical expression with variables , The most important thing is ExpressionContext class , This class is used to save variables in expressions , The test code and running interface are shown in the following figure .

	  try
      {
    
          ExpressionContext context = new ExpressionContext();

          foreach(DataGridViewRow dgvr in dgvParams.Rows)
          {
    
              decimal tmpValue = 0;

              if(string.IsNullOrEmpty(Convert.ToString(dgvr.Cells[0].Value))
                  || !decimal.TryParse(Convert.ToString(dgvr.Cells[1].Value),out tmpValue))
              {
    
                  continue;
              }

              context.Variables[Convert.ToString(dgvr.Cells[0].Value)] = tmpValue;
          }
          
          IDynamicExpression calcResult = context.CompileDynamic(txtExpression.Text);
          txtResult.Text =Convert.ToString(calcResult.Evaluate());
      }
      catch (ExpressionCompileException ex)
      {
    
          if (ex.Reason == CompileExceptionReason.SyntaxError)
          {
    
              txtResult.Text = "Check your expression syntax" + "\r\n" + ex.Message;
          }
          else
          {
    
              txtResult.Text = ex.Message;
          }

      }

  Flee It's more powerful , This article only tests the simplest of these uses , I will continue to learn in the future Flee Usage of .

reference ：
[1]https://github.com/mparlak/Flee
[2]https://github.com/mparlak/Flee/wiki/Examples