When I use StreamReader` for some reason the file I use isn't read. can I get any help?

I tried deleting the file and putting it in again but it didn't work

CodePudding user response：

line is initialized to "", so the while loop is never entered. The condition should be line != null, not line == null like you currently have.

CodePudding user response：

Your while loop condition is not correct it should be while(line != null), first of all line is initialized to empty string ("") so with current code the loop is never entered, secondary line = b.ReadLine(); should not be null until the file ends - from the StreamReader.ReadLine docs:

Returns String
The next line from the input stream, or null if the end of the input stream is reached.

Also this makes inner check if(line != null) obsolete.

CodePudding user response：

Your while is not correct; just have a look:

...
string line = "";

// line is NOT null (it's empty) that's why
// while will not enter at all
while (line == null) 
{
...
}

Let's change while into for, let pesky line (which is declared out of loop, is check in while, in if etc.) be a loop variable:

// Wrap IDisposable into using; do not Close them expplicitly
using (StreamReader b = new StreamReader("students.txt")) 
{
    ...
    for (string line = b.ReadLine(); line != null; line = b.ReadLine()) 
    {
        if (line == "2") { num2  ; }
    ...
    }
    ...
}