The below code when checked in "Add watch" window shows the right value (100), but the value is not assigned to variable _countVar, the value is 0 which is incorrect.
Can someone tell me what is wrong in my code:
string _strVariable = "New York";
var _countVar = nestList
.SelectMany((List<object> w) => w)
.Count(w => w == _strVariable);
Well, if w is of type object in
...
.SelectMany((List<object> w) => w) // w is object
.Count(w => w == _strVariable); // if w has the same reference as _strVariable
you actually compare references, not strings values. If strings don't share the same reference (they are not Interned), they will be considered different:
object x = "abc";
// some manipulations to prevent the compiler to intern x and y strings
string y = ("abc" + " ").Trim(); // "abc", note that y has the same value as x
Console.Write(x == y ? "equals" : $"{x} <> {y}");
Outcome:
abc <> abc
To compare strings values put string.Equals:
string _strVariable = "New York";
var _countVar = nestList
.SelectMany(list => list)
.Count(city => string.Equals(city, _strVariable));