# isDigit {#isdigit}

**Parent topic:**[Functions](../../Functions/category.md)

## Syntax {#syntax}

`isDigit(X)`

## Arguments {#arguments}

**X** is a STRING scalar or vector.

## Details {#details}

Return "true" if all characters in the string are numbers. For null values of the STRING type, return "false".

## Examples {#examples}

```
isDigit("123456");
// output: true

isDigit("1And1");
// output: false

isDigit("10.05");
// output: false

isDigit(string());
// output: false
```

