External Interfaces Reference |
Get field number, given field name in structure array
C Syntax
Arguments
array_ptr
Pointer to a structure mxArray
.
field_name
The name of a field in the structure mxArray
.
Returns
The field number of the specified field_name,
on success. The first field has a field number of 0, the second field has a field number of 1, and so on. Returns -1
on failure. Common causes of failure include:
array_ptr
that does not point to a structure mxArray
. Call mxIsStruct
to determine if array_ptr
points to a structure mxArray
.
field_name
of a nonexistent field.
Description
If you know the name of a field but do not know its field number, call mxGetFieldNumber
. Conversely, if you know the field number but do not know its field name, call mxGetFieldNameByNumber
.
For example, consider a MATLAB structure initialized to
patient.name = 'John Doe'; patient.billing = 127.00; patient.test = [79 75 73; 180 178 177.5; 220 210 205];
The field name
has a field number of 0; the field billing
has a field number of 1; and the field test
has a field number of 2. If you call mxGetFieldNumber
and specify a field name of anything other than name
, billing
, or test
, then mxGetFieldNumber
returns -1
.
where index
is zero if you have a one-by-one structure.
Examples
See mxcreatestructarray.c
in the mx
subdirectory of the examples
directory.
See Also
mxGetField
, mxGetFieldByNumber
, mxGetFieldNameByNumber
, mxGetNumberOfFields
, mxSetField
, mxSetFieldByNumber
mxGetFieldNameByNumber | mxGetImagData |
© 1994-2005 The MathWorks, Inc.