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# substring(to:)

Returns a new string containing the characters of the receiver up to, but not including, the one at a given index.

```
func substring(to: Int) -> String
```

## Parameters

`to`

An index. The value must lie within the bounds of the receiver, or be equal to the length of the receiver.

    Raises an [`rangeException`](/documentation/Foundation/NSExceptionName/rangeException)     if (    `anIndex`     - 1) lies beyond the end of the receiver.

## Return Value

A new string containing the characters of the receiver up to, but not including, the one at `anIndex`. If `anIndex` is equal to the length of the string, returns a copy of the receiver.

---

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