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>
", 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>
-b --bar draw an underbar and an overbar
", 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"},
}