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I clearly understand "Pattern-based" approach that uses C# compiler when it dealing with the foreach statement. And from C# Language Specification (section 8.8.4) it is clear that first of all C# compiler tries to find GetEnumerator method and only then tries to find IEnumerable<T> and IEnumerable interfaces. But its unclear for me, why C# compiler treats string separately (because the String class contains a method GetEnumerator that returns CharEnumerator and it also implements IEnumerable<char> and IEnumerable interfces): string s = "1234"; foreach(char c in s) Console.WriteLine(c); converts to string s = "1234"; for(int i = 0; i < s.Length; i++) Console.WriteLine(s[i]); But I can't find any exceptions in Language Specification regarding the String class. Could someone give some insights about this solution? I tried with the C# 4 compiler. Here is the IL code for the previous code snippet: IL_0000: ldstr "1234" IL_0005: stloc.0 IL_0006: ldloc.0 IL_0007: stloc.2 IL_0008: ldc.i4.0 IL_0009: stloc.3 IL_000A: br.s IL_001E IL_000C: ldloc.2 IL_000D: ldloc.3 IL_000E: callvirt System.String.get_Chars IL_0013: stloc.1 IL_0014: ldloc.1 IL_0015: call System.Console.WriteLine IL_001A: ldloc.3 IL_001B: ldc.i4.1 IL_001C: add IL_001D: stloc.3 IL_001E: ldloc.3 IL_001F: ldloc.2 IL_0020: callvirt System.String.get_Length IL_0025: blt.s IL_000C

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