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Golang Regexp Find Examples: FindAllString
Use the Find and FindAllString funcs on regexp. Loop over the results.Find. With regexp we are often trying to find strings within a larger string. We use patterns (passed to MustCompile) to determine which values match.
To use Find, we must have byte slices. This is inconvenient in some programs. We can use a method like FindAllString instead, to operate directly on strings.
Find example. Here we use Find. We try to find a 3-digit sequence that begins with the value 2. The Find method returns the leftmost matching sequence as a byte slice.
Important: With byte slices, we must convert them back to strings before printing them. This can be annoying.
Golang program that uses Find
package main
import (
"fmt"
"regexp"
)
func main() {
// Match 3-digit values starting with 2.
re := regexp.MustCompile("2\\d\\d")
// Use find to get leftmost match.
result := re.Find([]byte("123 124 125 205 211"))
// Convert back to string and print it.
fmt.Println(string(result))
}
Output
205
FindAllString. This func finds multiple matches of a pattern within a string. It returns the values in a slice—we can loop over it with a for-loop.For
String: We operate directly on strings with FindAllString the results are in a slice of strings, so we can print them with no conversion.
Golang program that uses FindAllString
package main
import (
"fmt"
"regexp"
)
func main() {
// Match 3-char values starting with digit 1.
re := regexp.MustCompile("1..")
// Find and loop over all matching strings.
results := re.FindAllString("123 124 125 200 211", -1)
for i := range(results) {
fmt.Println(results[i])
}
}
Output
123
124
125
A review. With Find-methods, we perform a search within the source string—the entire string is not matched as in MatchString(). We can test matches in a for-loop after the method call.Regexp
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