lancet/docs/formatter.md

# Formatter

formatter contains some functions for data formatting.

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## Source:

-   [https://github.com/duke-git/lancet/blob/main/formatter/formatter.go](https://github.com/duke-git/lancet/blob/main/formatter/formatter.go)

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## Usage:

```go
import (
    "github.com/duke-git/lancet/v2/formatter"
)
```

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## Index

-   [Comma](#Comma)
-   [Pretty](#Pretty)
-   [PrettyToWriter](#PrettyToWriter)

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## Documentation

### <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>

<b>Signature:</b>

```go
func Comma[T constraints.Float | constraints.Integer | string](value T, symbol string) string
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/formatter"
)

func main() {
    result1 := formatter.Comma("123", "")
    result2 := formatter.Comma("12345", "$")
    result3 := formatter.Comma(1234567, "￥")

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 123
    // $12,345
    // ￥1,234,567
}
```

### <span id="Pretty">Pretty</span>

<p>Pretty data to JSON string.</p>

<b>Signature:</b>

```go
func Pretty(v any) (string, error)
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/formatter"
)

func main() {
    result1, _ := formatter.Pretty([]string{"a", "b", "c"})
    result2, _ := formatter.Pretty(map[string]int{"a": 1})

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // [
    //     "a",
    //     "b",
    //     "c"
    // ]
    // {
    //     "a": 1
    // }
}
```

### <span id="PrettyToWriter">PrettyToWriter</span>

<p>Pretty encode data to writer.</p>

<b>Signature:</b>

```go
func PrettyToWriter(v any, out io.Writer) error
```

<b>Example:</b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/formatter"
)

func main() {
    type User struct {
        Name string `json:"name"`
        Aage uint   `json:"age"`
    }
    user := User{Name: "King", Aage: 10000}

    buf := &bytes.Buffer{}
    err := formatter.PrettyToWriter(user, buf)

    fmt.Println(buf)
    fmt.Println(err)

    // Output:
    // {
    //     "name": "King",
    //     "age": 10000
    // }
    //
    // <nil>
}
```