> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sageprotocol.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# String

> Offers string manipulation, validation, and helper functions used across packages.

```rust theme={null}
use std::string;
```

<Tip>
  Explore this module further in the Mover Registry: @sage/utils
</Tip>

## Constants

Number difference between lowercase (e.g. "a") and uppercase (e.g. "A") values.

```rust theme={null}
const CHAR_CASE_OFFSET: u8 = 0x20;
```

Number representation of 'a'.

```rust theme={null}
const CHAR_LOWER_A: u8 = 0x61;
```

Number representation of 'z'.

```rust theme={null}
const CHAR_LOWER_Z: u8 = 0x7A;
```

Number representation of 'A'.

```rust theme={null}
const CHAR_UPPER_A: u8 = 0x41;
```

Number representation of 'Z'.

```rust theme={null}
const CHAR_UPPER_Z: u8 = 0x5A;
```

Number representation of '0'.

```rust theme={null}
const CHAR_ZERO: u8 = 0x30;
```

Number representation of '9'.

```rust theme={null}
const CHAR_NINE: u8 = 0x39;
```

Number representation of '-'.

```rust theme={null}
const CHAR_DASH: u8 = 0x2D;
```

## Functions

### `is_valid_name`

Returns true or false based on whether the name is valid.

```rust theme={null}
public fun is_valid_name(name: &std::string::String, min_length: u64, max_length: u64): bool
```

<Expandable title="Implementation">
  ```rust theme={null}
    public fun is_valid_name(
        name: &String,
        min_length: u64,
        max_length: u64
    ): bool {
        let len = name.length();
        let name_bytes = name.as_bytes();
        let mut index = 0;

        if (!(len >= min_length && len <= max_length)) {
            return false
        };

        while (index < len) {
            let character = name_bytes[index];
            let is_valid_character =
                (CHAR_UPPER_A <= character && character <= CHAR_UPPER_Z)
                || (CHAR_LOWER_A <= character && character <= CHAR_LOWER_Z)
                || (CHAR_ZERO <= character && character <= CHAR_NINE)
                || (character == CHAR_DASH && index != 0 && index != len - 1);

            if (!is_valid_character) {
                return false
            };

            index = index + 1;
        };

        true
    }
  ```
</Expandable>

### `to_lowercase`

Returns the lowercase value of the passed String.

```rust theme={null}
public fun to_lowercase(name: &std::string::String): std::string::String
```

<Expandable title="Implementation">
  ```rust theme={null}
    public fun to_lowercase(
        name: &String
    ): String {
        let len = name.length();
        let name_bytes = name.as_bytes();
        let mut index = 0;

        let mut lowercase_bytes = vector::empty<u8>();

        while (index < len) {
            let character = name_bytes[index];

            let lowercase = if (
                CHAR_UPPER_A <= character && character <= CHAR_UPPER_Z
            ) {
                character + CHAR_CASE_OFFSET
            } else {
                character
            };

            lowercase_bytes.push_back(lowercase);

            index = index + 1;
        };

        utf8(lowercase_bytes)
    }
  ```
</Expandable>

### `to_uppercase`

Returns the uppercase value of the passed String.

```rust theme={null}
public fun to_uppercase(name: &std::string::String): std::string::String
```

<Expandable title="Implementation">
  ```rust theme={null}
    public fun to_uppercase(
        name: &String
    ): String {
        let len = name.length();
        let name_bytes = name.as_bytes();
        let mut index = 0;

        let mut lowercase_bytes = vector::empty<u8>();

        while (index < len) {
            let character = name_bytes[index];

            let lowercase = if (
                CHAR_LOWER_A <= character && character <= CHAR_LOWER_Z
            ) {
                character - CHAR_CASE_OFFSET
            } else {
                character
            };

            lowercase_bytes.push_back(lowercase);

            index = index + 1;
        };

        utf8(lowercase_bytes)
    }
  ```
</Expandable>