# isNull {#isnull}

## Syntax {#syntax}

`isNull(X)`

## Arguments {#arguments}

**X** is a scalar/pair/vector/matrix.

## Details {#details}

Return true if an element is null.

## Examples {#examples}

```
isNull(00i);
// output: true

isNull(1 NULL NULL 6 NULL 7);
// output: [false,true,true,false,true,false]

isNull(1/0);
// output: 1

x=1 NULL 5 NULL 4 6$2:3;
x;
```

|\#0|\#1|\#2|
|---|---|---|
|1|5|4|
|||6|

```
isNull(x);
```

|\#0|\#1|\#2|
|---|---|---|
|0|0|0|
|1|1|0|

Related functions: [hasNull](../h/hasNull.md), [nullFill](../n/nullFill.md)

