What is the difference between the two methods
Convert.ToBoolean()
and
Boolean.Parse()?
Is there any reason to use one or the other?
Additionally, are there any other type.Parse() methods that I should watch out for?
Thanks,
Matt
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3 Answers
Convert.ToBoolean(string) actually calls bool.Parse() anyway, so for non-null strings, there's no functional difference. (For null strings, Convert.ToBoolean() returns false, whereas bool.Parse() throws an ArgumentNullException.)
Given that fact, you should use bool.Parse() when you're certain that your input isn't null, since you save yourself one null check.
Convert.ToBoolean() of course has a number of other overloads that allow you to generate a bool from many other built-in types, whereas Parse() is for strings only.
In terms of type.Parse() methods you should look out for, all the built-in numeric types have Parse() as well as TryParse() methods. DateTime has those, as well as the additional ParseExact()/TryParseExact() methods, which allow you specify an expected format for the date.
2 Comments
brandeded
Thanks for the details. So, there is no difference in performance between the two, or you could say extremely small gains by using Boolean.Parse(string)?
dlev
@mbrownnyc You would get a very minor (likely imperceptible) gain by using
Parse() if you're certain the input isn't a null string. If you're not sure, just use ToBoolean(), since it will do the check for you. And if you don't want a null string to result in false, then perform the check yourself, and then call Parse() if it's not null.Here is the short demo:
object ex1 = "True"; Console.WriteLine(Convert.ToBoolean(ex1)); // True Console.WriteLine(bool.Parse(ex1.ToString())); // True object ex2 = "true"; Console.WriteLine(Convert.ToBoolean(ex2)); // True Console.WriteLine(bool.Parse(ex2.ToString())); // True object ex3 = 1; Console.WriteLine(Convert.ToBoolean(ex3)); // True Console.WriteLine(bool.Parse(ex3.ToString())); // Unhandled Exception: System.FormatException object ex3 = "1"; Console.WriteLine(Convert.ToBoolean(ex3)); // An unhandled exception of type 'System.FormatException' occurred Console.WriteLine(bool.Parse(ex3.ToString())); // Unhandled Exception: System.FormatException object ex4 = "False"; Console.WriteLine(Convert.ToBoolean(ex4)); // False Console.WriteLine(bool.Parse(ex4.ToString())); // False object ex5 = "false"; Console.WriteLine(Convert.ToBoolean(ex5)); // False Console.WriteLine(bool.Parse(ex5.ToString())); // False object ex6 = 0; Console.WriteLine(Convert.ToBoolean(ex6)); // False Console.WriteLine(bool.Parse(ex6.ToString())); // Unhandled Exception: System.FormatException object ex7 = null; Console.WriteLine(Convert.ToBoolean(ex7)); // False Console.WriteLine(bool.Parse(ex7.ToString())); // Unhandled Exception: System.NullReferenceException Note: There are also two properties of bool TrueString and FalseString, but be careful, because bool.TrueString != "true", only bool.TrueString == "True"
Console.WriteLine(bool.TrueString); // True Console.WriteLine(bool.FalseString); // False 
2 Comments
Robert McKee
Convert.ToBoolean("1"); // Format Exception
Arne Peirs
Convert.ToBoolean("2"); will also return a truthy value. I know that booleans are sometimes referenced as 0 and 1, but you never know that someone mistypes something.Boolean.Parse() will convert a string representation of a logical boolean value to a boolean value. Convert.ToBoolean() has multiple overloads that will convert primitive types to their boolean equivalent.
Most, if not all, of the primitive types in C# have an associated *.Parse/Convert.To* method that serve the same purpose as Boolean.Parse()/Convert.ToBoolean().
