c# - Why is this code throwing an InvalidOperationException? -

i think code should make viewbag.test property equal "no match", instead throws invalidoperationexception.

why this?

string str = "hello1,hello,hello2"; string = "hello5"; string retval = str.split(",".tochararray(), stringsplitoptions.removeemptyentries)                    .first(p => p.equals(another)); if (str == another) {    viewbag.test = "match"; } else {    viewbag.test = "no match"; //this not happen when should } 

as can see here, first method throws invalidoperationexception when sequence on called empty. since no element of result of split equals hello5, result empty list. using first on list throw exception.

consider using firstordefault, instead (documented here), which, instead of throwing exception when sequence empty, returns default value type of enumerable. in case, result of call null, , should check in rest of code.

it might cleaner still use any linq method (documented here), returns bool.

string str = "hello1,hello,hello2"; string = "hello5"; bool retval = str.split(",".tochararray(), stringsplitoptions.removeemptyentries)                    .any(p => p.equals(another)); if (retval) {    viewbag.test = "match"; } else {    viewbag.test = "no match"; //not work } 

and obligatory 1 liner using ternary operator:

string str = "hello1,hello,hello2"; string = "hello5"; viewbag.test = str.split(",".tochararray(), stringsplitoptions.removeemptyentries)                    .any(p => p == another) ? "match" : "no match"; 

note used == here compare strings, considered more idiomatic in c#.