struct (MATLAB Functions)

Create structure array

Syntax

s = struct('field1', values1, 'field2', values2, ...)
s = struct('field1', {}, 'field2', {}, ...)
struct([])
struct(obj)

Description

s = struct('field1', values1, 'field2', values2, ...) creates a structure array with the specified fields and values. The value arrays values1, values2, etc., must be cell arrays of the same size or scalar cells. Corresponding elements of the value arrays are placed into corresponding structure array elements. The size of the resulting structure is the same size as the value cell arrays or 1-by-1 if none of the values is a cell.

Structure field names must begin with a letter, and are case-sensitive. The rest of the name may contain letters, numerals, and underscore characters. Use the namelengthmax function to determine the maximum length of a field name.

s = struct('field1', {}, 'field2', {}, ...) creates an empty structure with fields field1, field2, ...

struct([]) creates an empty structure with no fields.

struct(obj) converts the object obj into its equivalent structure. The class information is lost.

Remarks

The most common way to access the data in a structure is by specifying the name of the field that you want to reference. Another means of accessing structure data is to use dynamic field names. These names express the field as a variable expression that MATLAB evaluates at run-time.

To create fields that contain cell arrays, place the cell arrays within a value cell array. For instance, to create a 1-by-1 structure, type

s = struct('strings',{{'hello','yes'}},'lengths',[5 3])
s = 
   strings: {'hello'  'yes'}
   lengths: [5 3]

Examples

The command

s = struct('type', {'big','little'}, 'color', {'red'}, ...
    'x', {3 4})

produces a structure array s:

s = 
1x2 struct array with fields:
    type
    color
    x

The value arrays have been distributed among the fields of s:

s(1)
ans = 
      type: 'big'
    color: 'red'
        x: 3
s(2)
ans = 
      type: 'little'
    color: 'red'
        x: 4

Similarly, the command

```
a.b = struct('z', {});
```

produces an empty structure a.b with field z.

a.b
ans = 
      0x0 struct array with fields:
          z

strtrim struct2cell