Golang : Increment string example
Problem:
You need to create "copies" of a file, prevent user from overwriting files accidentally or need duplicate database content which has unique titles or slugs. Having increment string function is helpful in this kind of situation. How to do that?
Solution:
Increments a string by appending a number to it or increasing the number.
Below is a function to increment the string value that you can use or adapt to your own Golang code.
package main
import (
"fmt"
"os"
"strconv"
"strings"
)
func incrementString(str string, separator string, first int) string {
// set default values
// see https://www.socketloop.com/tutorials/golang-proper-way-to-set-function-argument-default-value
if separator == "" {
separator = "_"
}
if first == 0 || first < 0 {
first = 1
}
// test to see if str already has integer suffix(ends with _#)
test := strings.SplitN(str, separator, 2)
if len(test) >= 2 {
// increase file counter by 1
i, err := strconv.Atoi(test[1])
if err != nil {
fmt.Println(err)
os.Exit(1)
}
increased := i + first
return test[0] + separator + strconv.Itoa(increased)
} else {
return str + separator + strconv.Itoa(first)
}
}
func main() {
result := incrementString("file", "_", 0)
fmt.Println(result)
result = incrementString("file", "-", 2)
fmt.Println(result)
// increase by 1
result = incrementString("file_2", "", 1)
fmt.Println(result)
// increase by 2
result = incrementString("file_2", "", 2)
fmt.Println(result)
// increase by 100
result = incrementString("file_3", "", 100)
fmt.Println(result)
// change separator to # sign
result = incrementString("imagefiles", "#", 10)
fmt.Println(result)
// will NOT accept negative number. will change to default value of 1
result = incrementString("imagefiles", "#", -99)
fmt.Println(result)
}
Output:
file_1
file-2
file_3
file_4
file_103
imagefiles#10
imagefiles#1
Happy coding!
References:
See also : Golang : How to check if a string starts or ends with certain characters or words?
By Adam Ng
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