Ex 4.8
Modify charcount to count letters, digits, and so on in their Unicode categories, using functions like unicode.IsLetter.
package main
import (
"bufio"
"fmt"
"io"
"os"
"unicode"
)
func main() {
counts := make(map[string]int) // counts of Unicode characters
invalid, letter, digit, mark, other := 0, 0, 0, 0, 0 // count of invalid UTF-8 characters
in := bufio.NewReader(os.Stdin)
for {
r, n, err := in.ReadRune() // returns rune, nbytes, error
if err == io.EOF {
break
}
if err != nil {
fmt.Fprintf(os.Stderr, "charcount: %v\n", err)
os.Exit(1)
}
if r == unicode.ReplacementChar && n == 1 {
invalid++
continue
} else if unicode.IsLetter(r) {
letter++
} else if unicode.IsDigit(r) {
digit++
} else if unicode.IsMark(r) {
mark++
} else {
other++
fmt.Println(r)
}
}
counts["invalid"] = invalid
counts["letter"] = letter
counts["digit"] = digit
counts["mark"] = mark
counts["other"] = other
for c, n := range counts {
fmt.Printf("%s\t:%d\n", c, n)
}
}
./ex4.8
sdfwwer 1434jipi三是奇偶i问
32
10
invalid :0
letter :17
digit :4
mark :0
other :2
- 显然汉字也被认为是letter
- 终端模拟EOF 为 ctrl + d
Ex 4.9
Write a program wordfreq to report the frequency of each word in an input text file. Call input.Split(bufio.ScanWords) before the first call to Scan to break the input into words instead of lines.
package main
import (
"bufio"
"fmt"
"strings"
)
func main() {
words := make(map[string]int)
input := "foo bar baz foo 我们 foo 我们"
scanner := bufio.NewScanner(strings.NewReader(input))
scanner.Split(bufio.ScanWords)
for scanner.Scan() {
//fmt.Println(scanner.Text())
words[scanner.Text()]++
}
for k, v := range words {
fmt.Printf("%s : %d\n", k, v)
}
}
$ go run wordfreq.go
baz : 1
我们 : 2
foo : 3
bar : 1
Ex4.13
The JSON-based web service of the Open Movie Database lets you s https://omdbapi.com/ for a movie by name and download its poster image. Write a tool poster that downloads the poster image for the movie named on the command line.
package main
import (
"encoding/json"
"fmt"
"io"
"net/http"
"os"
)
const OmdbAPI = "http://www.omdbapi.com/?i=tt3896198&apikey=7b94e6bd&t="
type Movie struct {
Title string
Year string
Poster string
Response string
Errormsg string `json:"Error,omitempty"`
}
func main() {
for i := 1; i < len(os.Args); i++ {
url := OmdbAPI + os.Args[i]
resp, err := http.Get(url)
if err != nil {
fmt.Println("http get error ", err)
return
}
defer resp.Body.Close()
var result Movie
err = json.NewDecoder(resp.Body).Decode(&result)
if err != nil {
fmt.Println("decode failed")
return
}
fmt.Printf("%#v\n", result)
fmt.Printf("%v\n", result)
if result.Response == "false" {
fmt.Println(result.Errormsg)
} else {
fmt.Println("starting download poster")
result.Poster = "https://gss1.bdstatic.com/9vo3dSag_xI4khGkpoWK1HF6hhy/baike/c0%3Dbaike92%2C5%2C5%2C92%2C30/sign=5a60b1a4cf8065386fe7ac41f6b4ca21/fd039245d688d43f4ee7a518781ed21b0ff43b89.jpg"
posterres, err := http.Get(result.Poster)
if err != nil {
fmt.Println("get poster url error, download failed", err)
return
} else {
filename := result.Title + ".jpg"
f, err := os.Create(filename)
if err != nil {
fmt.Println("create file error")
return
}
io.Copy(f, posterres.Body)
}
}
}
}
$ ./ex4.13 triangle triangleeeee
main.Movie{Title:"Triangle", Year:"2009", Poster:"https://images-na.ssl-images-amazon.com/images/M/MV5BY2VlODI5ZmMtZDExYS00OWI4LWJiMWItZWZkZWRkNzlmZWI2XkEyXkFqcGdeQXVyMTQxNzMzNDI@._V1_SX300.jpg", Response:"True", Errormsg:""}
{Triangle 2009 https://images-na.ssl-images-amazon.com/images/M/MV5BY2VlODI5ZmMtZDExYS00OWI4LWJiMWItZWZkZWRkNzlmZWI2XkEyXkFqcGdeQXVyMTQxNzMzNDI@._V1_SX300.jpg True }
starting download poster
download finished
main.Movie{Title:"", Year:"", Poster:"", Response:"False", Errormsg:"Movie not found!"}
{ False Movie not found!}
Movie not found!
Ex 4.14
Create a web server that queries GitHub once and then allows navigation of the list of bug reports, milestones, and users.
package main
import (
"encoding/json"
"fmt"
temp2 "html/template"
"log"
"net/http"
"net/url"
"os"
"strings"
temp1 "text/template"
"time"
)
const IssuesURL = "https://api.github.com/search/issues"
//!+template
const templ1 = `{{.TotalCount}} issues:
{{range .Items}}----------------------------------------
Number: {{.Number}}
User: {{.User.Login}}
Title: {{.Title | printf "%.64s"}}
Age: {{.CreatedAt | daysAgo}} days
Milestone: {{.Milestone.Title}}
{{end}}`
const templ2 = `
{{.TotalCount}} issues
#
State
User
Title
Milestone
{{range .Items}}
{{.Number}}
{{.State}}
{{.User.Login}}
{{.Title}}
{{.Milestone.Title}}
{{end}}
`
//!-template
type IssuesSearchResult struct {
TotalCount int `json:"total_count"`
Items []*Issue
}
type Issue struct {
Number int
HTMLURL string `json:"html_url"`
Title string
State string
User *User
CreatedAt time.Time `json:"created_at"`
Body string // in Markdown format
Milestone *Milestone
}
type User struct {
Login string
HTMLURL string `json:"html_url"`
}
type Milestone struct {
Title string
HTMLURL string `json:"html_url"`
}
var report1 = temp1.Must(temp1.New("issuelist1").
Funcs(temp1.FuncMap{"daysAgo": daysAgo}).
Parse(templ1))
var report2 = temp2.Must(temp2.New("issuelist2").
Funcs(temp2.FuncMap{"daysAgo": daysAgo}).
Parse(templ2))
func main() {
result, err := SearchIssues(os.Args[1:])
if err != nil {
log.Fatal(err)
}
f1, err := os.Create("report.txt")
if err := report1.Execute(f1, result); err != nil {
log.Fatal(err)
}
f2, err := os.Create("report.html")
if err := report2.Execute(f2, result); err != nil {
log.Fatal(err)
}
}
func daysAgo(t time.Time) int {
return int(time.Since(t).Hours() / 24)
}
// SearchIssues queries the GitHub issue tracker.
func SearchIssues(terms []string) (*IssuesSearchResult, error) {
q := url.QueryEscape(strings.Join(terms, " "))
resp, err := http.Get(IssuesURL + "?q=" + q)
if err != nil {
return nil, err
}
// We must close resp.Body on all execution paths.
// (Chapter 5 presents 'defer', which makes this simpler.)
if resp.StatusCode != http.StatusOK {
resp.Body.Close()
return nil, fmt.Errorf("search query failed: %s", resp.Status)
}
var result IssuesSearchResult
if err := json.NewDecoder(resp.Body).Decode(&result); err != nil {
resp.Body.Close()
return nil, err
}
resp.Body.Close()
return &result, nil
}
//report.txt
41 issues:
----------------------------------------
Number: 23188
User: ianlancetaylor
Title: cmd/compile: incorrect order of evaluation according to spec
Age: 7 days
Milestone: Go1.11
----------------------------------------
Number: 23183
User: terinjokes
Title: net/http: muxer no longer redirects host patterns in go1.10
Age: 7 days
Milestone: Go1.10
----------------------------------------
Number: 23181
User: hirochachacha
Title: cmd/buildid: rewrite algorithm is broken
Age: 7 days
Milestone: Go1.10
----------------------------------------
Number: 23180
User: aarzilli
Title: cmd/go: go test -c does not apply specified gcflags to all packa
Age: 7 days
Milestone: Go1.10
----------------------------------------
Number: 23166
User: mvdan
Title: x/tools/go/ssa/interp: tests consistently failing on darwin
Age: 8 days
Milestone: Go1.10
----------------------------------------
Number: 23146
User: bradfitz
Title: cmd/vet: stderr spam during testing
Age: 12 days
Milestone: Go1.10
----------------------------------------
Number: 23122
User: rsc
Title: all: remove support for OS X 10.8 and 10.9
Age: 13 days
Milestone: Go1.11
----------------------------------------
Number: 23098
User: mikioh
Title: runtime: loop over allp causes a nil pointer dereference crash
Age: 15 days
Milestone: Go1.10
----------------------------------------
Number: 23037
User: zolotov
Title: cmd/go: add JSON output for building package failures while runn
Age: 19 days
Milestone: Go1.10
----------------------------------------
Number: 23036
User: zolotov
Title: cmd/test2json: filtering out testing service messages or mark th
Age: 19 days
Milestone: Go1.10
----------------------------------------
Number: 23011
User: bradfitz
Title: build: announce end of support for old macOS releases
Age: 21 days
Milestone: Go1.11
----------------------------------------
Number: 23010
User: rsc
Title: net/http: ResponseWriter panics in WriteHeaders that were former
Age: 21 days
Milestone: Go1.10
----------------------------------------
Number: 23009
User: rsc
Title: net/http/httputil: ReverseProxy change conflicts with future Rev
Age: 21 days
Milestone: Go1.10
----------------------------------------
Number: 22984
User: rsc
Title: cmd/go: test -json not cached
Age: 22 days
Milestone: Go1.10
----------------------------------------
Number: 22924
User: chipaca
Title: syscall: on linux 386 doesn't support syscalls that don't fail
Age: 27 days
Milestone: Go1.11
----------------------------------------
Number: 22781
User: pciet
Title: runtime: fatal error: sweep increased allocation count, go1.9.x
Age: 39 days
Milestone: Go1.9.3
----------------------------------------
Number: 22637
User: ianlancetaylor
Title: crypto: examine and probably remove OpenSSL derived code
Age: 48 days
Milestone: Go1.10
----------------------------------------
Number: 22487
User: tklauser
Title: lib/time: update tzdata before 1.10 release
Age: 58 days
Milestone: Go1.10
----------------------------------------
Number: 22475
User: rsc
Title: cmd/go: include GOROOT in linkActionID hash
Age: 59 days
Milestone: Go1.10
----------------------------------------
Number: 22472
User: rsc
Title: cmd/go: implement gccgo support for content-based staleness
Age: 60 days
Milestone: Go1.10
----------------------------------------
Number: 22444
User: griesemer
Title: cmd/compile: missing wrapper function for call of literal method
Age: 62 days
Milestone: Go1.11
----------------------------------------
Number: 22429
User: TheTincho
Title: cmd/compile: invalid instruction error for FMOVD when compiling
Age: 63 days
Milestone: Go1.9.3
----------------------------------------
Number: 22349
User: alexbrainman
Title: net: ipStackCapabilities.probe creates sockets that can escape i
Age: 68 days
Milestone: Go1.10
----------------------------------------
Number: 22224
User: siebenmann
Title: cmd/go: build failure on amd64 Linux with an error in TestTwoGop
Age: 76 days
Milestone: Go1.10
----------------------------------------
Number: 22204
User: tmm1
Title: runtime: sigpanic during GC on android/arm64
Age: 77 days
Milestone: Go1.10
----------------------------------------
Number: 22155
User: rsc
Title: cmd/go: GOROOT override using linker -X flag is probably not rig
Age: 82 days
Milestone: Go1.10
----------------------------------------
Number: 21431
User: josharian
Title: runtime: stack split at a bad time on mipsle
Age: 135 days
Milestone: Go1.10
----------------------------------------
Number: 21282
User: dsnet
Title: cmd/compile: incorrect type assertions on conflicting package na
Age: 146 days
Milestone: Go1.11
----------------------------------------
Number: 21221
User: vibhavp
Title: cmd/compile: internal compiler error: constant type mismatch whe
Age: 150 days
Milestone: Go1.11
----------------------------------------
Number: 20790
User: mikioh
Title: net: DefaultResolver.Lookup{Host,IPAddr} and LookupHost fail to
Age: 185 days
Milestone: Go1.11
//report.html
41 issues
