Find and replace

The example in this subsection will search the provided text for two variations of a given string and replace it with another string. The program will be named findReplace.go and will actually use Go regular expressions. The main reason for using the regexp.Compile() function, in this case, is that it greatly simplifies things and allows you to access your text only once.

The first part of the findReplace.go program is as follows:

package main 
 
import ( 
   "fmt" 
   "os" 
   "regexp" 
) 

The next part is as follows:

func main() { 
 
   var s [3]string 
   s[0] = "1 b 3" 
   s[1] = "11 a B 14 1 1" 
   s[2] = "b 2 -3 B -5" 
 
   parse, err := regexp.Compile("[bB]")

 
 
   if err != nil { 
         fmt.Printf("Error compiling RE: %s\n", err) 
         os.Exit(-1) 
   } 

The previous Go code will find every occurrence of an uppercase B or a lowercase b ([bB]). Note that there is also regexp.MustCompile() that works like regexp.Compile(). However, regexp.MustCompile() does not return an error variable; it just panics if the given expression is erroneous and cannot be parsed. As a result, regexp.Compile() is a better choice.

The last part is as follows:

   for i := 0; i < len(s); i++ { 
         temp := parse.ReplaceAllString(s[i], "C") 
         fmt.Println(temp) 
   } 
} 

Here you replace each match with an uppercase C using parse.ReplaceAllString().

Executing findReplace.go generates the expected output:

$ go run findReplace.go
1 C 3
11 a C 14 1 1
C 2 -3 C -5