#include <stdio.h>
#include <math.h>
#include <string.h>
#include <malloc.h>

#define MAX_VALUE 256

void main(int argc, char **argv)
{
    char infile[30];
    int i,j;

    FILE *ifp;
    unsigned char*img;   
    int size;
    int    freq[MAX_VALUE];
    float prob[MAX_VALUE];

    float entropy;

    strcpy(infile , "GABE.RAW");//打开语音文件
    ifp = fopen(infile,"rb");
    if(ifp ==NULL)//如果文件是空，则报错
    {
       printf("Image file %s cannot be opened for input.\n", infile);
       getchar();
       return;
    }

    //计算语音文件大小
    fseek(ifp, 0, SEEK_END);
    size = ftell(ifp);
    ++size;
    fseek(ifp, 0, SEEK_SET);

    img = (unsigned char*) malloc (size * sizeof(unsigned char));
    if (img == NULL)
    {
        printf("无法打开文件.\n");
        fclose(ifp);
        getchar();
        return;
    }

    //读取文件
    fread(img, sizeof(unsigned char), size, ifp);
    fclose(ifp);

    //计算灰度值的概率
    for(j=0; j<MAX_VALUE; j++)
        freq[j] = 0;

    for(i=0; i<size; i++)
        freq[ img[i] ] ++;   

    free(img);

    for(j=0; j<MAX_VALUE; j++)
        prob[j] = (float)freq[j] / (float)size;

   //计算熵
   entropy = 0.0;
   for(i=0; i<MAX_VALUE; i++)
      if(prob[i] > 0.0)
         entropy = entropy - prob[i] * (float) log( (double) prob[i]);
         entropy = entropy/ (float) log ((double) 2.0);
    printf("first-order entropy of the speech is: %f\n",entropy);
getchar();
}

这个不懂。。。。。帮顶啊