Set field value in structure array, given index and field number
#include "matrix.h" void mxSetFieldByNumber(mxArray *pm, mwIndex index, int fieldnumber, mxArray *pvalue);
#include "fintrf.h" subroutine mxSetFieldByNumber(pm, index, fieldnumber, pvalue) mwPointer pm, pvalue mwIndex index integer*4 fieldnumber
pmPointer to a structure mxArray. Call
mxIsStruct to determine whether
pm points to a structure
mxArray.
indexIndex of the desired element.
In C,
the first element of an mxArray has an index of 0.
The index of the last element is N-1,
where N is the number of elements in the array.
In Fortran, the first element of an mxArray has
an index of 1. The index of
the last element is N, where N is
the number of elements in the array.
See mxCalcSingleSubscript for details on calculating
an index.
fieldnumberPosition of the field in the structure. The field must exist in the structure.
In C, the first field within each element has a
fieldnumber of 0. The
fieldnumber of the last is N-1,
where N is the number of fields.
In Fortran, the first field within each element has a
fieldnumber of 1. The
fieldnumber of the last is N,
where N is the number of fields.
pvaluePointer to the mxArray containing the data you want to
assign.
Use mxSetFieldByNumber to assign the contents of
pvalue to the field specified by fieldnumber
of element index. mxSetFieldByNumber is like
mxSetField; however, the function identifies the field by
position number, not by name.
If you want to replace the contents at fieldnumber, then first free
the memory of the existing data. Use the mxGetFieldByNumber
function to get a pointer to the field, call mxDestroyArray on the
pointer, then call mxSetFieldByNumber to assign the new
value.
You cannot assign pvalue to more than one field in a structure or
to more than one element in the mxArray. If you want to assign the
contents of pvalue to multiple fields, then use the
mxDuplicateArray function to make copies of the data then call
mxSetFieldByNumber on each copy.
To free memory for structures created using this function, call
mxDestroyArray only on the structure array. Do not call
mxDestroyArray on the array pvalue points to. If you
do, then MATLAB® attempts to free the same memory twice, which can corrupt
memory.
Note
Inputs to a MEX-file are constant read-only mxArrays.
Do not modify the inputs. Using mxSetCell* or mxSetField* functions
to modify the cells or fields of a MATLAB argument causes unpredictable
results.
In C, calling:
mxSetField(pa, index, "field_name", new_value_pa);
is equivalent to calling:
field_num = mxGetFieldNumber(pa, "field_name"); mxSetFieldByNumber(pa, index, field_num, new_value_pa);
In Fortran, calling:
mxSetField(pm, index, 'fieldname', newvalue)
is equivalent to calling:
fieldnum = mxGetFieldNumber(pm, 'fieldname') mxSetFieldByNumber(pm, index, fieldnum, newvalue)
mxCreateStructArray, mxCreateStructMatrix, mxGetFieldByNumber, mxGetFieldNameByNumber, mxGetFieldNumber, mxGetNumberOfFields, mxIsStruct,
mxSetField,
mxDestroyArray,
mxCalcSingleSubscript