Canonicalize CIDR: Difference between revisions

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@@ Line 203: / Line 203: @@
     "fmt"
     "log"
-    "os"
     "strconv"
     "strings"
 )
 func check(err error) {
     if err != nil {
         log.Fatal(err)
     }
 }
+// canonicalize a CIDR block: make sure none of the host bits are set
-func main() {
+func canonicalize(cidr string) string {
-    // canonicalize a CIDR block: make sure none of the host bits are set
-    var cidr string
-    if len(os.Args) > 1 {
-        cidr = os.Args[1]
-    } else {
-        log.Fatal("Please pass the CIDR to be canonicalized.")
-    }
     // dotted-decimal / bits in network part
     split := strings.Split(cidr, "/")
@@ Line 249: / Line 241: @@
     }
-    // and output
+    // and return
-    fmt.Printf("%s/%s\n", strings.Join(canon, "."), split[1])
+    return strings.Join(canon, ".") + "/" + split[1]
+}
+func main() {
+    tests := []string{
+        "87.70.141.1/22",
+        "36.18.154.103/12",
+        "62.62.197.11/29",
+        "67.137.119.181/4",
+        "161.214.74.21/24",
+        "184.232.176.184/18",
+    }
+    for _, test := range tests {
+        fmt.Printf("%-18s -> %s\n", test, canonicalize(test))
+    }
 }</lang>
 {{out}}
 <pre>
-$ go run canonicalize_cidr.go 87.70.141.1/22
+.70.141.1/22     -> 87.70.140.0/22
+.18.154.103/12   -> 36.16.0.0/12
-.70.140.0/22
+.62.197.11/29    -> 62.62.197.8/29
+.137.119.181/4   -> 64.0.0.0/4
+.214.74.21/24   -> 161.214.74.0/24
+.232.176.184/18 -> 184.232.128.0/18
 </pre>