C# - Foreach won't let me use string for string [closed]

When you use foreach with a string, you do NOT get lines! Nor should you. After all, a string is a sequence of characters.

Specifically, foreach works by calling GetEnumerator() and when you call string.GetEnumerator() you get a CharEnumerator (ie a sequence of characters).

When you need to loop through lines (instead of characters) of a string, you can use a StringReader (not StreamReader).

But in this case you have a file. To loop through the lines of a file, do NOT use File.ReadAllText(), and do NOT use File.ReadAllLines(), as suggested elsewhere, at least as your first choice.

Instead, look at File.ReadLines() (no All), again — at least as your first choice. This saves you from needing to load the entire file into memory all at the same time.

Additionally, looking at the final sample, as a matter of style it's much better if the method accepts the file_name as an argument and returns the data as a result.

Put it all together and we end up with this:

public static IEnumerable<string> LoadFile(string file_Name)
{
    return File.ReadLines(file_Name).
         Where(line => line != string.Empty && !line.StartsWith("//") );   
}

var file = LoadFile("medallion.txt");

Even better, we probably don't want to accept lines that are only white space or only have whitespace before the comment marker (while still preserving indentation that may be significant):

public static IEnumerable<string> LoadFile(string file_Name)
{
    return File.ReadLines(file_Name).
         Where(line => {
             var trimmed = line.Trim();
             return trimmed != string.Empty && !trimmed.StartsWith("//"); 
         });  
}

var file = LoadFile("medallion.txt");

But since you say you're a beginner, you may need it to look more like this:

public static List<string> LoadFile(string file_Name)
{
    var result = new List<string>();
    var lines = File.ReadLines(file_Name);
    foreach(string line in lines)
    {
        if (line != string.Empty && !line.StartsWith("//") )
        { 
            result.Add(line);
        }
    }
    return result;  
}

var file = LoadFile("medallion.txt");

Which is more code to be less efficient, but now the only advanced feature you need to know about is generic collections, which is still a concept typcially introduced to college CS students in the first or second year.

When you iterate over a string, you iterate over each character in the string. So, if you were to iterate a string hello!, you would get the following chars: h e l l o !

File.ReadAllText reads the raw file content as a single string, which is also iterated by a char.

Use File.ReadAllLines instead, which returns a string array representing each line of a file:

string[] fileContent = File.ReadAllLines(file_name);
foreach (string line in fileContent)
{
    // do something with line
}

If you have the following contents in a file:

hello
world
!

then File.ReadAllLines would return a string array, consisting of these strings: hello world !