refactor: for loop can be modernized using range over int (#4392)

Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>

Author: wanghaolong613

benchmarks_test.go

@@ -154,7 +154,7 @@ func runRequest(B *testing.B, r *Engine, method, path string) {
 	w := newMockWriter()
 	B.ReportAllocs()
 	B.ResetTimer()
-	for i := 0; i < B.N; i++ {
+	for B.Loop() {
 		r.ServeHTTP(w, req)
 	}
 }

binding/default_validator.go

@@ -27,7 +27,7 @@ func (err SliceValidationError) Error() string {
 	}
 
 	var b strings.Builder
-	for i := 0; i < len(err); i++ {
+	for i := range len(err) {
 		if err[i] != nil {
 			if b.Len() > 0 {
 				b.WriteString("\n")
@@ -58,7 +58,7 @@ func (v *defaultValidator) ValidateStruct(obj any) error {
 	case reflect.Slice, reflect.Array:
 		count := value.Len()
 		validateRet := make(SliceValidationError, 0)
-		for i := 0; i < count; i++ {
+		for i := range count {
 			if err := v.ValidateStruct(value.Index(i).Interface()); err != nil {
 				validateRet = append(validateRet, err)
 			}

binding/form_mapping.go

@@ -119,7 +119,7 @@ func mapping(value reflect.Value, field reflect.StructField, setter setter, tag
 		tValue := value.Type()
 
 		var isSet bool
-		for i := 0; i < value.NumField(); i++ {
+		for i := range value.NumField() {
 			sf := tValue.Field(i)
 			if sf.PkgPath != "" && !sf.Anonymous { // unexported
 				continue

context_test.go

@@ -3677,22 +3677,22 @@ func BenchmarkGetMapFromFormData(b *testing.B) {
 
 	// Test case 3: Large dataset with many bracket keys
 	largeData := make(map[string][]string)
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		key := fmt.Sprintf("ids[%d]", i)
 		largeData[key] = []string{fmt.Sprintf("value%d", i)}
 	}
-	for i := 0; i < 50; i++ {
+	for i := range 50 {
 		key := fmt.Sprintf("names[%d]", i)
 		largeData[key] = []string{fmt.Sprintf("name%d", i)}
 	}
-	for i := 0; i < 25; i++ {
+	for i := range 25 {
 		key := fmt.Sprintf("other[key%d]", i)
 		largeData[key] = []string{fmt.Sprintf("other%d", i)}
 	}
 
 	// Test case 4: Dataset with many non-matching keys (worst case)
 	worstCaseData := make(map[string][]string)
-	for i := 0; i < 100; i++ {
+	for i := range 100 {
 		key := fmt.Sprintf("nonmatching%d", i)
 		worstCaseData[key] = []string{fmt.Sprintf("value%d", i)}
 	}
@@ -3728,7 +3728,7 @@ func BenchmarkGetMapFromFormData(b *testing.B) {
 	for _, bm := range benchmarks {
 		b.Run(bm.name, func(b *testing.B) {
 			b.ReportAllocs()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				_, _ = getMapFromFormData(bm.data, bm.key)
 			}
 		})

gin_integration_test.go

@@ -400,7 +400,7 @@ func TestConcurrentHandleContext(t *testing.T) {
 	var wg sync.WaitGroup
 	iterations := 200
 	wg.Add(iterations)
-	for i := 0; i < iterations; i++ {
+	for range iterations {
 		go func() {
 			req, err := http.NewRequest(http.MethodGet, "/", nil)
 			assert.NoError(t, err)

internal/bytesconv/bytesconv_test.go

@@ -30,7 +30,7 @@ func rawStrToBytes(s string) []byte {
 
 func TestBytesToString(t *testing.T) {
 	data := make([]byte, 1024)
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		_, err := cRand.Read(data)
 		if err != nil {
 			t.Fatal(err)
@@ -79,7 +79,7 @@ func RandStringBytesMaskImprSrcSB(n int) string {
 }
 
 func TestStringToBytes(t *testing.T) {
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		s := RandStringBytesMaskImprSrcSB(64)
 		if !bytes.Equal(rawStrToBytes(s), StringToBytes(s)) {
 			t.Fatal("don't match")

utils.go

@@ -162,7 +162,7 @@ func resolveAddress(addr []string) string {
 
 // https://stackoverflow.com/questions/53069040/checking-a-string-contains-only-ascii-characters
 func isASCII(s string) bool {
-	for i := 0; i < len(s); i++ {
+	for i := range len(s) {
 		if s[i] > unicode.MaxASCII {
 			return false
 		}