# isfield

Determine if input is structure array field

## Syntax

``TF = isfield(S,field)``

## Description

example

````TF = isfield(S,field)` returns `1` if `field` is the name of a field of the structure array `S`. Otherwise, it returns `0`.If `field` is an array that contains multiple names and `S` is a structure array, then `TF` is a logical array that has the same size.If `S` is not a structure array, then `isfield` returns `0`.```

## Examples

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Create a structure.

```S.x = linspace(0,2*pi); S.y = sin(S.x); S.title = 'y = sin(x)'```
```S = struct with fields: x: [0 0.0635 0.1269 0.1904 0.2539 0.3173 0.3808 0.4443 0.5077 0.5712 0.6347 0.6981 0.7616 0.8251 0.8885 0.9520 1.0155 1.0789 1.1424 1.2059 1.2693 1.3328 1.3963 1.4597 1.5232 1.5867 1.6501 1.7136 1.7771 1.8405 1.9040 1.9675 ... ] (1x100 double) y: [0 0.0634 0.1266 0.1893 0.2511 0.3120 0.3717 0.4298 0.4862 0.5406 0.5929 0.6428 0.6901 0.7346 0.7761 0.8146 0.8497 0.8815 0.9096 0.9341 0.9549 0.9718 0.9848 0.9938 0.9989 0.9999 0.9969 0.9898 0.9788 0.9638 0.9450 0.9224 ... ] (1x100 double) title: 'y = sin(x)' ```

Determine if `'title'` is the name of a field of `S`.

`TF = isfield(S,'title')`
```TF = logical 1 ```

You can test multiple names in one call to the `isfield` function by specifying them in a cell array or string array.

```field = {'x','y','z','title','error'}; TF = isfield(S,field)```
```TF = 1x5 logical array 1 1 0 1 0 ```

## Input Arguments

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Structure array.

Potential field names, specified as a character vector, cell array of character vectors, or string array.

## Tips

• If the input argument `S` is an object, then `isfield` always returns `0`, even when `field` is the name of a property.

To determine if a name is the name of a property of an object, use the `isprop` function.

## Version History

Introduced before R2006a