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matlab从入门到精通第13章书后源码对初学者很有帮助

// 头文件
#include "mex.h"
#include "string.h"

#define MAXCHARS 80   /* 指定每个域可以包含的最大字符数 */

/* 接口函数  */
void mexFunction(int nlhs, mxArray *plhs[],
                 int nrhs, const mxArray *prhs[])
{
  const char **fnames;       /* 指向域名的指针 */
  const int  *dims;
  mxArray    *tmp, *fout;
  char       *pdata;
  int        ifield, jstruct, *classIDflags;
  int        NStructElems, nfields, ndim;
    
  /* 检查输入输出是否正确 */
  if (nrhs != 1)
    mexErrMsgTxt("One input required.");
  else if (nlhs > 1)
    mexErrMsgTxt("Too many output arguments.");
  else if (!mxIsStruct(prhs[0]))
    mexErrMsgTxt("Input must be a structure.");

  /* 获取输入数据 */
  nfields = mxGetNumberOfFields(prhs[0]);
  NStructElems = mxGetNumberOfElements(prhs[0]);

  /* 为classIDflags分配内存 */
  classIDflags = mxCalloc(nfields, sizeof(int));

  /* 检查区域是否空白，数据类型是否正确和一致，为每个域获取classID */
  for (ifield = 0; ifield < nfields; ifield++) {
    for (jstruct = 0; jstruct < NStructElems; jstruct++) {
      tmp = mxGetFieldByNumber(prhs[0], jstruct, ifield);
      if (tmp == NULL) {
        mexPrintf("%s%d\t%s%d\n",
            "FIELD:", ifield+1, "STRUCT INDEX :", jstruct+1);
        mexErrMsgTxt("Above field is empty!"); 
      } 
      if (jstruct == 0) {
        if ((!mxIsChar(tmp) && !mxIsNumeric(tmp)) || 
            mxIsSparse(tmp)) { 
          mexPrintf("%s%d\t%s%d\n", 
              "FIELD:", ifield+1, "STRUCT INDEX :", jstruct+1);
          mexErrMsgTxt("Above field must have either "
              "string or numeric non-sparse data.");
        }
        classIDflags[ifield] = mxGetClassID(tmp); 
      } else {
        if (mxGetClassID(tmp) != classIDflags[ifield]) {
          mexPrintf("%s%d\t%s%d\n", 
              "FIELD:", ifield+1, "STRUCT INDEX :", jstruct+1);
          mexErrMsgTxt("Inconsistent data type in above field!");
        } 
        else if (!mxIsChar(tmp) && ((mxIsComplex(tmp) || 
            mxGetNumberOfElements(tmp) != 1))) {
          mexPrintf("%s%d\t%s%d\n", 
              "FIELD:", ifield+1, "STRUCT INDEX :", jstruct+1);
          mexErrMsgTxt("Numeric data in above field "
              "must be scalar and noncomplex!");
        }
      }
    }
  }

  /* 为保存指针分配内存 */
  fnames = mxCalloc(nfields, sizeof(*fnames));

  /* 获得每个字段名指针 */
  for (ifield = 0; ifield < nfields; ifield++) {
    fnames[ifield] = mxGetFieldNameByNumber(prhs[0],ifield);
  }

  /* 创建输出的1x1结构体矩阵 */
  plhs[0] = mxCreateStructMatrix(1, 1, nfields, fnames);
  mxFree(fnames);
  ndim = mxGetNumberOfDimensions(prhs[0]);
  dims = mxGetDimensions(prhs[0]);
  for (ifield = 0; ifield < nfields; ifield++) {
    /* 创建单元或数值矩阵 */
    if (classIDflags[ifield] == mxCHAR_CLASS) {
      fout = mxCreateCellArray(ndim, dims);
    } else {
      fout = mxCreateNumericArray(ndim, dims, 
          classIDflags[ifield], mxREAL);
      pdata = mxGetData(fout);
    }

    /* 从输入结构体矩阵中拷贝数据 */
    for (jstruct = 0; jstruct < NStructElems; jstruct++) {
      tmp = mxGetFieldByNumber(prhs[0],jstruct,ifield);
      if (mxIsChar(tmp)) {
        mxSetCell(fout, jstruct, mxDuplicateArray(tmp));
      } else {
        size_t     sizebuf;
        sizebuf = mxGetElementSize(tmp);
        memcpy(pdata, mxGetData(tmp), sizebuf);
        pdata += sizebuf;
      }
    }

    /* Set each field in output structure */
    mxSetFieldByNumber(plhs[0], 0, ifield, fout);
  }
  mxFree(classIDflags);
  return;
}