英文:
Alternative to using strings.Builder in conjunction with fmt.Sprintf
问题
我正在学习Go语言中的strings包，并尝试构建一个简单的错误消息。
我了解到strings.Builder是一种非常高效的字符串连接方式，而fmt.Sprintf则可以进行字符串插值。
说到这里，我想了解最佳的字符串连接方式。例如，这是我创建的代码：
func generateValidationErrorMessage(err error) string {
errors := []string{}
for _, err := range err.(validator.ValidationErrors) {
var b strings.Builder
b.WriteString(fmt.Sprintf("[%s] failed validation [%s]", err.Field(), err.ActualTag()))
if err.Param() != "" {
b.WriteString(fmt.Sprintf("[%s]", err.Param()))
}
errors = append(errors, b.String())
}
return strings.Join(errors, "; ")
}
还有其他更好的方法吗？使用s1 + s2被认为更差吗？
英文:
I am learning about the strings package in Go and I am trying to build up a simple error message.
I read that strings.Builder is a very eficient way to join strings, and that fmt.Sprintf lets me do some string interpolation.
With that said, I want to understand the best way to join a lot of strings together. For example here is what I create:
func generateValidationErrorMessage(err error) string {
errors := []string{}
for _, err := range err.(validator.ValidationErrors) {
var b strings.Builder
b.WriteString(fmt.Sprintf("[%s] failed validation [%s]", err.Field(), err.ActualTag()))
if err.Param() != "" {
b.WriteString(fmt.Sprintf("[%s]", err.Param()))
}
errors = append(errors, b.String())
}
return strings.Join(errors, "; ")
}
Is there another/better way to do this? Is using s1 + s2 considered worse?
答案1
得分: 2
你可以使用fmt直接将内容打印到strings.Builder中。使用fmt.Fprintf(&builder, "格式字符串", args)。
以Fprint...开头的fmt函数，表示"文件打印"，允许你将内容打印到io.Writer，比如os.File或strings.Builder。
此外，不需要使用多个builder并在最后将它们的字符串连接起来，只需使用一个单独的builder并不断向其中写入内容。如果你想要添加分隔符，可以在循环内轻松实现：
var builder strings.Builder
for i, v := range values {
if i > 0 {
// 除非是第一项，否则在其前面添加分隔符。
fmt.Fprint(&builder, "; ")
}
fmt.Fprintf(&builder, "一些格式 %v", v)
}
var output = builder.String()
英文:
You can use fmt to print directly to the strings.Builder. Use fmt.Fprintf(&builder, "format string", args).
The fmt functions beginning with Fprint..., meaning "file print", allow you to print to an io.Writer such as a os.File or strings.Builder.
Also, rather than using multiple builders and joining all their strings at the end, just use a single builder and keep writing to it. If you want to add a separator, you can do so easily within the loop:
var builder strings.Builder
for i, v := range values {
if i > 0 {
// unless this is the first item, add the separator before it.
fmt.Fprint(&builder, "; ")
}
fmt.Fprintf(&builder, "some format %v", v)
}
var output = builder.String()
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