String equality with null handling

c# .net string null equality
Brady Moritz picture Brady Moritz · Mar 3, 2013 · Viewed 48.8k times · Source

I will often use this code to compare a string: 

if(!string.IsNullOrEmpty(str1) && str1.Equals(str2)){
    //they are equal, do my thing
}

This handles the null case first etc.

Is there a cleaner way to do string comparison, perhaps with a single method call that will handle possible null values? I simply want to know that the strings are not equal if the testing value is null.

(I'm having dejavu that I may have asked this before, I apologize if so)

Update: In my case, the str2 is a known good string to compare to, so I don't need to check it for null. str1 is the "unknown" string which may be null, so I want to say "str1 does not equal str2" in the cases where str1 is null...

Answer

SLaks picture SLaks · Mar 3, 2013

Unlike Java, C# strings override the == operator:

if (str1 == str2)

If you want a case-insensitive comparison:

if (String.Equals(str1, str2, StringComparison.OrdinalIgnoreCase)

Related questions

How to do ToString for a possibly null object?

Is there a simple way of doing the following: String s = myObj == null ? "" : myObj.ToString(); I know I can do the following, but I really consider it as a hack: String s = "" + myObj; It would be great if Convert.ToString() …

Read More
string.Empty vs null.Which one do you use?

Recently a colleague at work told me not to use string.Empty when setting a string variable but use null as it pollutes the stack? He says don't do string myString=string.Empty; but do string mystring=null; Does it …

Read More
Why is it Valid to Concatenate Null Strings but not to Call "null.ToString()"?

This is valid C# code var bob = "abc" + null + null + null + "123"; // abc123 This is not valid C# code var wtf = null.ToString(); // compiler error Why is the first statement valid?

Read More