D: add countLettersInTextFile.d

d-programming/countLettersInTextFile.d

@@ -0,0 +1,16 @@
+import std.algorithm.iteration : filter;
+import std.algorithm.searching : count;
+import std.ascii : isAlpha, isWhite;
+import std.file : read;
+import std.stdio : writefln;
+
+void main()
+{
+	auto fileContent = cast(string)read("file.txt");
+	auto totalLetters =
+		count(filter!(a => isAlpha(a) || isWhite(a))(fileContent));
+	auto percentage = (totalLetters * 100) / cast(double)fileContent.length;
+
+	writefln("Percentage of letters: %.0f", percentage);
+}
+