array contains element but IndexOf returns -1

Question

I have a string array lines of which one item may contain the value Mister or Misses .

var lines = "3.3. 3 - 3 88C Mister Molitor D For Ne Les Text".Split(' ');

Console.WriteLine(lines.Contains("Mister") || lines.Contains("Misses")); 

returns true . Now I want to find the index of Mister , respectively Misses , using

var index = lines.IndexOf("Mister");

(I didn't put the code for Misses here for the sake of simplicity)

However, index always is -1 (despite the item's existence in the array). So I thought there must be something different to try (I even added ToLower() , which however cannot be the reason as lines.Contains() otherwise'd return false):

var index = lines.FindIndex(x => x.ToLower() == "mister");

But still... index = -1 . This is driving me crazy! We definitely have the array containing the item, yet I can't find the index.

Answer 1

The following is true

lines.Contains("Mister") || lines.Contains("Misses")

because your string literal contains the word Misses . That being said, when you call the IndexOf on the lines passing as a parameter the Mister you get -1 , because Mister is not contained in lines .

Answer 2

Assuming that you do have text with the word "Mister" in it somewhere; the following code should work:

string[] lines = "3.3. 3 - 3 88C Misses Molitor D For Ne Les Text".Split(' ');      
Console.WriteLine(lines.Contains("Mister") || lines.Contains("Misses"));
var idx = Array.FindIndex(lines, l => l == "Misses");

Console.WriteLine(idx);

Answer 3

This code worked for me. Pos has the value of 5. containsOne is true and containsTwo is false.

var lines = "3.3. 3 - 3 88C Mister Molitor D For Ne Les Text".Split(' ');
var pos = Array.FindIndex(lines, c => c.Equals("Mister"));

var containsOne = lines.Contains("Mister") || lines.Contains("Misses");
var containsTwo = lines.Contains("Mister") && lines.Contains("Misses");

For more information on the FindIndex method have a look at this page on MSDN