vb.net - Assign a math operator to a variable without IF - System.MissingMemberException -


i trying send operation sign via string variable (cal_operation) error.

notes:

  • label1 hold result
  • text1 hold 1 of 2 numbers make calculation on them
  • text2 hold second number of 2 numbers make calculation on them
  • cal_operation string hold operation sign (- or + or / or - )

the code is:

dim cal_operation string public newops = new dictionary(of string, func(of double, double, double))() {         {"+", function(x, y) x + y},         {"-", function(x, y) x - y},         {"*", function(x, y) x * y},         {"/", function(x, y) x / y} 

and have radio buttons assign operation string variable
in button insert code

radiobutton1_checkedchanged(sender object, e eventargs) handles radiobutton1.checkedchanged    cal_operation = "+"     dim op1 = newops(cal_operation)    label1.text = cstr(op1(cdbl(textbox1.text), cdbl(textbox2.text))) end sub 

but error

an unhandled exception of type 'system.missingmemberexception' occurred in microsoft.visualbasic.dll additional information: no default member found type 'func(of double,double,double)'.

what reason , solution?

you need change declaration of newops dictionary , explicit on type

public newops dictionary(of string, func(of double, double, double)) =         new dictionary(of string, func(of double, double, double))() { {"+", function(x, y) x + y}, {"-", function(x, y) x - y}, {"*", function(x, y) x * y}, {"/", function(x, y) x / y}} 

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