matcreat.asv

matlab从入门到精通第13章书后源码对初学者很有帮助

/*
 * MAT-file creation program
 *
 * Calling syntax:
 *
 *   matcreat
 *
 * This program demonstrates the use of the following functions:
 *
 *  matClose
 *  matGetVariable
 *  matOpen
 *  matPutVariable
 *  matPutVariableAsGlobal
 */
#include <stdio.h>
#include <string.h> /* 字符串比较strcmp() */
#include <stdlib.h> /* 用于EXIT_FAILURE, EXIT_SUCCESS */
#include "mat.h"

#define BUFSIZE 256

int main() {
  //为MAT文件定义指针 
  MATFile *pmat;
  //定义结构体指针
  mxArray *pa1, *pa2, *pa3;
  //定义双精度变量
  double data[9] = { 1.0, 4.0, 7.0, 2.0, 5.0, 8.0, 3.0, 6.0, 9.0 };
  const char *file = "mattest.mat";
  char str[BUFSIZE];
  int status; 

  // 以标准的C输出格式输出数据
  printf("Creating file %s...\n\n", file);
  // 打开写文件
  pmat = matOpen(file, "w");
  if (pmat == NULL) {
    printf("Error creating file %s\n", file);
    printf("(Do you have write permission in this directory?)\n");
    return(EXIT_FAILURE);
  }

  pa1 = mxCreateDoubleMatrix(3,3,mxREAL);
  if (pa1 == NULL) {
      printf("%s : Out of memory on line %d\n", __FILE__, 
              __LINE__); 
      printf("Unable to create mxArray.\n");
      return(EXIT_FAILURE);
  }

  pa2 = mxCreateDoubleMatrix(3,3,mxREAL);
  if (pa2 == NULL) {
      printf("%s : Out of memory on line %d\n", __FILE__, 
             __LINE__);
      printf("Unable to create mxArray.\n");
      return(EXIT_FAILURE);
  }
  //将data缓冲区中的内容复制到pa2所指的实部缓冲区内 
  memcpy((void *)(mxGetPr(pa2)), (void *)data, sizeof(data));
  
  //为pa3创建指针
  pa3 = mxCreateString("MATLAB: the language of technical 
                         computing");
  if (pa3 == NULL) {
      printf("%s :  Out of memory on line %d\n", __FILE__, 
              __LINE__);
      printf("Unable to create string mxArray.\n");
      return(EXIT_FAILURE);
  }

  status = matPutVariable(pmat, "LocalDouble", pa1);
  if (status != 0) {
      printf("%s :  Error using matPutVariable on line %d\n", 
              __FILE__, __LINE__);
      return(EXIT_FAILURE);
  }  
  
  status = matPutVariableAsGlobal(pmat, "GlobalDouble", pa2);
  if (status != 0) {
      printf("Error using matPutVariableAsGlobal\n");
      return(EXIT_FAILURE);
  } 
  
  status = matPutVariable(pmat, "LocalString", pa3);
  if (status != 0) {
      printf("%s :  Error using matPutVariable on line %d\n", 
              __FILE__, __LINE__);
      return(EXIT_FAILURE);
  } 
  
  /*
   * Ooops! we need to copy data before writing the array.  (Well,
   * ok, this was really intentional.) This demonstrates that
   * matPutVariable will overwrite an existing array in a 
MAT-file.
   */
  memcpy((void *)(mxGetPr(pa1)), (void *)data, sizeof(data));
  status = matPutVariable(pmat, "LocalDouble", pa1);
  if (status != 0) {
      printf("%s :  Error using matPutVariable on line %d\n", 
              __FILE__, __LINE__);
      return(EXIT_FAILURE);
  } 
  
  /* Clean up. */
  mxDestroyArray(pa1);
  mxDestroyArray(pa2);
  mxDestroyArray(pa3);

  if (matClose(pmat) != 0) {
    printf("Error closing file %s\n",file);
    return(EXIT_FAILURE);
  }

  /* Re-open file and verify its contents with matGetVariable. */
  pmat = matOpen(file, "r");
  if (pmat == NULL) {
    printf("Error reopening file %s\n", file);
    return(EXIT_FAILURE);
  }

  /* Read in each array we just wrote. */
  pa1 = matGetVariable(pmat, "LocalDouble");
  if (pa1 == NULL) {
    printf("Error reading existing matrix LocalDouble\n");
    return(EXIT_FAILURE);
  }
  if (mxGetNumberOfDimensions(pa1) != 2) {
    printf("Error saving matrix: result does not have two 
            dimensions\n");
    return(EXIT_FAILURE);
  }

  pa2 = matGetVariable(pmat, "GlobalDouble");
  if (pa2 == NULL) {
    printf("Error reading existing matrix GlobalDouble\n");
    return(EXIT_FAILURE);
  }
  if (!(mxIsFromGlobalWS(pa2))) {
    printf("Error saving global matrix: result is not global\n");
    return(EXIT_FAILURE);
  }

  pa3 = matGetVariable(pmat, "LocalString");
  if (pa3 == NULL) {
    printf("Error reading existing matrix LocalString\n");
    return(EXIT_FAILURE);
  }
  
  status = mxGetString(pa3, str, sizeof(str));
  if(status != 0) {
      printf("Not enough space. String is truncated.");
      return(EXIT_FAILURE);
  }
  if (strcmp(str, "MATLAB: the language of technical 
             computing")) {
    printf("Error saving string: result has incorrect 
            contents\n");
    return(EXIT_FAILURE);
  }

  /* Clean up before exit. */
  mxDestroyArray(pa1);
  mxDestroyArray(pa2);
  mxDestroyArray(pa3);

  if (matClose(pmat) != 0) {
    printf("Error closing file %s\n",file);
    return(EXIT_FAILURE);
  }
  printf("Done\n");
  return(EXIT_SUCCESS);
}