初识Go

意外关注到一位牛人的微信，提到了2014年他推荐的编程语言是Go。于是乎饶有兴趣的淘了一本书《Go语言程序设计》，学习起来。

第一章的练习题我的答案如下：

 // Copyright © 2010-12 Qtrac Ltd.
 //
 // This program or package and any associated files are licensed under the
 // Apache License, Version 2.0 (the "License"); you may not use these files
 // except in compliance with the License. You can get a copy of the License
 // at: http://www.apache.org/licenses/LICENSE-2.0.
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package main

 import (
     "fmt"
     "log"
     "os"
     "path/filepath"
     "strings"
 )

 func main() {
     if len(os.Args) == 1 {
         fmt.Printf("usage: %s <whole-number>\n", filepath.Base(os.Args[0]))
         os.Exit(1)
     }

     drawBar := false
     stringOfDigits := ""

     if len(os.Args) == 2 {
         if os.Args[1] == "-h" || os.Args[1] == "--help" {
             fmt.Printf("usage: %s [-b|--bar] <whole-number>\n-b --bar draw an underbar and an overbar\n", filepath.Base(os.Args[0]))
             os.Exit(1)
         } else {
             drawBar = false
             stringOfDigits = os.Args[1]
         }
     }

     if len(os.Args) == 3 {
         if os.Args[1] == "-b" || os.Args[1] == "--bar" {
             drawBar = true
             stringOfDigits = os.Args[2]
         }
     }

     for row := range bigDigits[0] {

         line := ""
         for column := range stringOfDigits {
             digit := stringOfDigits[column] - '0'
             if 0 <= digit && digit <= 9 {
                 line += bigDigits[digit][row] + "  "
             } else {
                 log.Fatal("invalid whole number")
             }
         }

         if drawBar && row == 0 {
             fmt.Println(strings.Repeat("*", len(line)))
         }
         fmt.Println(line)
         if drawBar && row == len(bigDigits[0])-1 {
             fmt.Println(strings.Repeat("*", len(line)))
         }
     }

     if drawBar {
     }
 }

 var bigDigits = [][]string{
     {"  000  ",
         " 0   0 ",
         "0     0",
         "0     0",
         "0     0",
         " 0   0 ",
         "  000  "},
     {" 1 ", "11 ", " 1 ", " 1 ", " 1 ", " 1 ", "111"},
     {" 222 ", "2   2", "   2 ", "  2  ", " 2   ", "2    ", "22222"},
     {" 333 ", "3   3", "    3", "  33 ", "    3", "3   3", " 333 "},
     {"   4  ", "  44  ", " 4 4  ", "4  4  ", "444444", "   4  ",
         "   4  "},
     {"55555", "5    ", "5    ", " 555 ", "    5", "5   5", " 555 "},
     {" 666 ", "6    ", "6    ", "6666 ", "6   6", "6   6", " 666 "},
     {"77777", "    7", "   7 ", "  7  ", " 7   ", "7    ", "7    "},
     {" 888 ", "8   8", "8   8", " 888 ", "8   8", "8   8", " 888 "},
     {" 9999", "9   9", "9   9", " 9999", "    9", "    9", "    9"},
 }

答案源码