doc: rename parameter name of Comma

README.md

@@ -763,7 +763,7 @@ import "github.com/duke-git/lancet/v2/formatter"
 
 #### Function list:
 
--   **<big>Comma</big>** : add comma to a number value by every 3 numbers from right, ahead by symbol char.
+-   **<big>Comma</big>** : add comma to a number value by every 3 numbers from right, ahead by a prefix symbol char.
     [[doc](https://github.com/duke-git/lancet/blob/main/docs/en/api/packages/formatter.md#Comma)]
     [[play](https://go.dev/play/p/eRD5k2vzUVX)]
 -   **<big>Pretty</big>** : pretty print data to JSON string.

README_zh-CN.md

@@ -764,7 +764,7 @@ import "github.com/duke-git/lancet/v2/formatter"
 
 #### 函数列表:
 
--   **<big>Comma</big>** : 用逗号每隔 3 位分割数字/字符串，支持前缀添加符号。
+-   **<big>Comma</big>** : 用逗号每隔 3 位分割数字/字符串，支持添加前缀符号。
     [[doc](https://github.com/duke-git/lancet/blob/main/docs/api/packages/formatter.md#Comma)]
     [[play](https://go.dev/play/p/eRD5k2vzUVX)]
 -   **<big>Pretty</big>** : 返回 pretty JSON 字符串。

docs/api/packages/formatter.md

@@ -37,12 +37,12 @@ import (
 
 ### <span id="Comma">Comma</span>
 
-<p>用逗号每隔3位分割数字/字符串，支持前缀添加符号。参数value必须是数字或者可以转为数字的字符串, 否则返回空字符串</p>
+<p>用逗号每隔3位分割数字/字符串，支持添加前缀符号。参数value必须是数字或者可以转为数字的字符串, 否则返回空字符串</p>
 
 <b>函数签名:</b>
 
 ```go
-func Comma[T constraints.Float | constraints.Integer | string](value T, symbol string) string
+func Comma[T constraints.Float | constraints.Integer | string](value T, prefixSymbol string) string
 ```
 
 <b>示例:<span style="float:right;display:inline-block;">[运行](https://go.dev/play/p/eRD5k2vzUVX)</span></b>

docs/en/api/packages/formatter.md

@@ -37,12 +37,12 @@ import (
 
 ### <span id="Comma">Comma</span>
 
-<p>Add comma to a number value by every 3 numbers from right to left. ahead by symbol char. if value is a invalid number string like "aa", return empty string.</p>
+<p>Add comma to a number value by every 3 numbers from right to left. ahead by a prefix symbol char. if value is a invalid number string like "aa", return empty string.</p>
 
 <b>Signature:</b>
 
 ```go
-func Comma[T constraints.Float | constraints.Integer | string](value T, symbol string) string
+func Comma[T constraints.Float | constraints.Integer | string](value T, prefixSymbol string) string
 ```
 
 <b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/eRD5k2vzUVX)</span></b>

formatter/formatter.go

@@ -14,11 +14,11 @@ import (
 	"golang.org/x/exp/constraints"
 )
 
-// Comma add comma to a number value by every 3 numbers from right. ahead by symbol char.
+// Comma add comma to a number value by every 3 numbers from right. ahead by prefix symbol char.
 // if value is invalid number string eg "aa", return empty string
 // Comma("12345", "$") => "$12,345", Comma(12345, "$") => "$12,345"
 // Play: https://go.dev/play/p/eRD5k2vzUVX
-func Comma[T constraints.Float | constraints.Integer | string](value T, symbol string) string {
+func Comma[T constraints.Float | constraints.Integer | string](value T, prefixSymbol string) string {
 	numString := convertor.ToString(value)
 
 	_, err := strconv.ParseFloat(numString, 64)
@@ -26,17 +26,26 @@ func Comma[T constraints.Float | constraints.Integer | string](value T, symbol s
 		return ""
 	}
 
+	isNegative := strings.HasPrefix(numString, "-")
+	if isNegative {
+		numString = numString[1:]
+	}
+
 	index := strings.Index(numString, ".")
 	if index == -1 {
 		index = len(numString)
 	}
 
 	for index > 3 {
-		index = index - 3
+		index -= 3
 		numString = numString[:index] + "," + numString[index:]
 	}
 
-	return symbol + numString
+	if isNegative {
+		numString = "-" + numString
+	}
+
+	return prefixSymbol + numString
 }
 
 // Pretty data to JSON string.

formatter/formatter_test.go

@@ -28,6 +28,10 @@ func TestComma(t *testing.T) {
 	assert.Equal("12,345.6789", Comma(+12345.6789, ""))
 	assert.Equal("12,345,678.9", Comma(12345678.9, ""))
 	assert.Equal("123,456,789,000", Comma(123456789000, ""))
+
+	assert.Equal("-999", Comma(-999, ""))
+	assert.Equal("-1,000", Comma(-1000, ""))
+	assert.Equal("-1,234,567", Comma(-1234567, ""))
 }
 
 func TestPretty(t *testing.T) {