matlab mxsetfieldbynumber函数语法发表matlab mxsetfieldbynumber函数相关文章
mxSetFieldByNumber (C and Fortran)
Set field value in structure array, given index and field number
#include "matrix.h" void mxSetFieldByNumber(mxArray *pm, mwIndex index, int fieldnumber, mxArray *pvalue);
subroutine mxSetFieldByNumber(pm, index, fieldnumber, pvalue) mwPointer pm, pvalue mwIndex index integer*4 fieldnumber
Pointer to a structure mxArray. Call mxIsStruct to determine whether pm points to a structure mxArray.
Index 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.
Position 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.
Pointer 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, you must 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, 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, MATLAB® attempts to free the same memory twice, which can corrupt memory.
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)
See the following examples in matlabroot/extern/examples/mx.