Can all 'for' loops be replaced with a LINQ statement?

Question

Is it possible to write the following \'foreach\' as a LINQ statement, and I guess the more general question can any for loop be replaced by a LINQ statement.

I\'m not i

Answer 1

Technically, yes.

Any foreach loop can be converted to LINQ by using a ForEach extension method,such as the one in MoreLinq.

If you only want to use "pure" LINQ (only the built-in extension methods), you can abuse the Aggregate extension method, like this:

foreach(type item in collection { statements }

type item;
collection.Aggregate(true, (j, itemTemp) => {
    item = itemTemp;
    statements
    return true;
);

This will correctly handle any foreach loop, even JaredPar's answer. EDIT: Unless it uses ref / out parameters, unsafe code, or yield return.
Don't you dare use this trick in real code.

---

In your specific case, you should use a string Join extension method, such as this one:

///
Appends a list of strings to a StringBuilder, separated by a separator string.
///The StringBuilder to append to.
///The strings to append.
///A string to append between the strings.
public static StringBuilder AppendJoin(this StringBuilder builder, IEnumerable strings, string separator) {
    if (builder == null) throw new ArgumentNullException("builder");
    if (strings == null) throw new ArgumentNullException("strings");
    if (separator == null) throw new ArgumentNullException("separator");

    bool first = true;

    foreach (var str in strings) {
        if (first)
            first = false;
        else
            builder.Append(separator);

        builder.Append(str);
    }

    return builder;
}

///
Combines a collection of strings into a single string.
public static string Join(this IEnumerable strings, string separator, Func selector) { return strings.Select(selector).Join(separator); }
///
Combines a collection of strings into a single string.
public static string Join(this IEnumerable strings, string separator) { return new StringBuilder().AppendJoin(strings, separator).ToString(); }