good good study, day day up!

vendor/gopl.io/ch4/dedup/main.go

@@ -0,0 +1,33 @@
+// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+// See page 96.
+
+// Dedup prints only one instance of each line; duplicates are removed.
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+//!+
+func main() {
+	seen := make(map[string]bool) // a set of strings
+	input := bufio.NewScanner(os.Stdin)
+	for input.Scan() {
+		line := input.Text()
+		if !seen[line] {
+			seen[line] = true
+			fmt.Println(line)
+		}
+	}
+
+	if err := input.Err(); err != nil {
+		fmt.Fprintf(os.Stderr, "dedup: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+//!-