go语言正则表达式regexp
regexp包里的正则表达式函数代码示例
package main
import (
"fmt"
"io/ioutil"
"net/http"
"os"
"regexp"
"strings"
)
/*func Match(pattern string, b []byte) (matched bool, error error)
func MatchReader(pattern string, r io.RuneReader) (matched bool, error error)
func MatchString(pattern string, s string) (matched bool, error error)*/
func IsIp(ip string) bool {
if m, _ := regexp.MatchString("^[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}.[0-9]{1,3}$", ip); !m {
return false
}
return true
}
func IsDigital(str string) string {
if m, _ := regexp.MatchString("^[0-9]+$", str); !m {
return "不是数字"
}
return "是数字"
}
func main1() {
fmt.Println(IsIp("192.168.172.88"))
fmt.Println(IsIp("192,167.12.11"))
fmt.Println(IsDigital("192,167.12.11"))
fmt.Println(IsDigital("192"))
}
/*以爬虫为例来说明如何使用正则来过滤或截取抓取到的数据*/
func main2() {
resp, err := http.Get("http://www.baidu.com")
if err != nil {
fmt.Println("http ger error")
return
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
fmt.Println("http read err")
return
}
src := string(body)
/*O_RDONLY int = syscall.O_RDONLY // open the file read-only.
O_WRONLY int = syscall.O_WRONLY // open the file write-only.
O_RDWR int = syscall.O_RDWR // open the file read-write.
O_APPEND int = syscall.O_APPEND // append data to the file when writing.
O_CREATE int = syscall.O_CREAT // create a new file if none exists.
O_EXCL int = syscall.O_EXCL // used with O_CREATE, file must not exist
O_SYNC int = syscall.O_SYNC // open for synchronous I/O.
O_TRUNC int = syscall.O_TRUNC // if possible, truncate file when opened.*/
file, _ := os.OpenFile("baidu.html", os.O_RDWR|os.O_CREATE, 0666)
defer file.Close()
file.WriteString(src)
//使用复杂的正则首先是Compile，它会解析正则表达式是否合法，如果正确，那么就会返回一个Regexp，
//然后就可以利用返回的Regexp在任意的字符串上面执行需要的操作
//将HTML标签全转换成小写
re, _ := regexp.Compile("\\<[\\S\\s]+?\\>")
src = re.ReplaceAllStringFunc(src, strings.ToLower)
//去除STYLE
re, _ = regexp.Compile("\\")
src = re.ReplaceAllString(src, "")
//去除SCRIPT
re, _ = regexp.Compile("\\")
src = re.ReplaceAllString(src, "")
//去除所有尖括号内的HTML代码，并换成换行符
re, _ = regexp.Compile("\\<[\\S\\s]+?\\>")
src = re.ReplaceAllString(src, "\n")
//去除连续的换行符
re, _ = regexp.Compile("\\s{2,}")
src = re.ReplaceAllString(src, "\n")
fmt.Println(strings.TrimSpace(src))
}
func main() {
a := "I am learning Go language"
fmt.Println([]byte(a))
re, _ := regexp.Compile("[a-z]{2,4}")
//查找符合正则的第一个
one := re.Find([]byte(a))
fmt.Println("Find:", string(one))
//查找符合正则的所有slice,n小于0表示返回全部符合的字符串，不然就是返回指定的长度
all := re.FindAll([]byte(a), -1)
for _, value := range all {
fmt.Println("FindAll", string(value))
}
//查找符合条件的index位置,开始位置和结束位置
index := re.FindIndex([]byte(a))
fmt.Println("FindIndex", index)
//查找符合条件的所有的index位置，n同上
allindex := re.FindAllIndex([]byte(a), -1)
fmt.Println("FindAllIndex", allindex)
re2, _ := regexp.Compile("am(.*)lang(.*)")
//查找Submatch,返回数组，第一个元素是匹配的全部元素，第二个元素是第一个()里面的，第三个是第二个()里面的
//下面的输出第一个元素是"am learning Go language"
//第二个元素是" learning Go "，注意包含空格的输出
//第三个元素是"uage"
submatch := re2.FindSubmatch([]byte(a))
fmt.Println("FindSubmatch", submatch)
for _, v := range submatch {
fmt.Println(string(v))
}
//定义和上面的FindIndex一样
submatchindex := re2.FindSubmatchIndex([]byte(a))
fmt.Println(submatchindex)
//FindAllSubmatch,查找所有符合条件的子匹配
submatchall := re2.FindAllSubmatch([]byte(a), -1)
fmt.Println(submatchall)
//FindAllSubmatchIndex,查找所有字匹配的index
submatchallindex := re2.FindAllSubmatchIndex([]byte(a), -1)
fmt.Println(submatchallindex)
src1 := []byte(`
call hello alice
hello bob
call hello eve
`)
pat := regexp.MustCompile(`(?m)(call)\s+(?P\w+)\s+(?P.+)\s*$`)
res := []byte{}
for _, s := range pat.FindAllSubmatchIndex(src1, -1) {
res = pat.Expand(res, []byte("$cmd('$arg')\n"), src1, s)
}
fmt.Println("expand ", string(res))
}