refactor(slice): simplify SliceValidationError Error method (#3910)

* Simplify SliceValidationError Error method

* Replace fmt.Fprintf with b.WriteString

---------

Co-authored-by: huangzw <huangzw@hsmap.com>
Co-authored-by: 1911860538 <alxps1911@163.com>

binding/default_validator.go

@@ -5,8 +5,8 @@
 package binding
 
 import (
-	"fmt"
 	"reflect"
+	"strconv"
 	"strings"
 	"sync"
 
@@ -22,25 +22,20 @@ type SliceValidationError []error
 
 // Error concatenates all error elements in SliceValidationError into a single string separated by \n.
 func (err SliceValidationError) Error() string {
-	n := len(err)
-	switch n {
-	case 0:
+	if len(err) == 0 {
 		return ""
-	default:
-		var b strings.Builder
-		if err[0] != nil {
-			fmt.Fprintf(&b, "[%d]: %s", 0, err[0].Error())
-		}
-		if n > 1 {
-			for i := 1; i < n; i++ {
-				if err[i] != nil {
-					b.WriteString("\n")
-					fmt.Fprintf(&b, "[%d]: %s", i, err[i].Error())
-				}
-			}
-		}
-		return b.String()
 	}
+
+	var b strings.Builder
+	for i := 0; i < len(err); i++ {
+		if err[i] != nil {
+			if b.Len() > 0 {
+				b.WriteString("\n")
+			}
+			b.WriteString("[" + strconv.Itoa(i) + "]: " + err[i].Error())
+		}
+	}
+	return b.String()
 }
 
 var _ StructValidator = (*defaultValidator)(nil)

binding/default_validator_benchmark_test.go

@@ -12,11 +12,15 @@ import (
 
 func BenchmarkSliceValidationError(b *testing.B) {
 	const size int = 100
+	e := make(SliceValidationError, size)
+	for j := 0; j < size; j++ {
+		e[j] = errors.New(strconv.Itoa(j))
+	}
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
 	for i := 0; i < b.N; i++ {
-		e := make(SliceValidationError, size)
-		for j := 0; j < size; j++ {
-			e[j] = errors.New(strconv.Itoa(j))
-		}
 		if len(e.Error()) == 0 {
 			b.Errorf("error")
 		}