c# - How to return a double or string for a method -

i have method:

public static double c(string val) {     return math.round(convert.todouble(val), 4); } 

where pass in string, , if double, want round return double, if string, want return string is. of parameters pass in strings start, how determine if string or double, , how rewrite methoed have return type flexible enough return either?

ideally, use type variant in vba, dont think there analog in c#.

the following try parse double. if returns true put double in output variable output; else return false means val isn't double , should use string val instead.

public static bool c(string val, out double output) {     if (double.tryparse(val, out output))     {         output = math.round(output, 4);         return true;     }     else     {         output = 0;         return false;     } } 

use this:

string val = "123.45678"; double output; if ( c(val, out output) ) {     // use double output } else {     // val isn't double, use val directly }