計算熵C

Question

我試圖找到任何給定文件的熵。但是，當我運行我的程序時，總是給出3.00000作爲答案。我有一段時間沒有使用C，但我不確定我在哪裏出錯。我現在擺弄了幾個小時。任何提示都會很棒，謝謝！

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

#define SIZE 256 

int entropy_calc(long byte_count[], int length) 
{ 
     float entropy; 
     float count; 
     int i; 

     /* entropy calculation */ 
     for (i = 0; i < SIZE; i++) 
     { 
      if (byte_count[i] != 0) 
      { 
       count = (float) byte_count[i]/(float) length; 
       entropy += -count * log2f(count); 
      } 
     } 
     return entropy; 
} 

int main(int argc, char **argv) 
{ 
    FILE   *inFile; 
    int    i;    
    int    j;    
    int    n;    // Bytes read by fread; 
    int    length;   // length of file 
    float   count; 
    float   entropy; 
    long   byte_count[SIZE]; 
    unsigned char buffer[1024]; 

    /* do this for all files */ 
    for(j = 1; j < argc; j++) 
    { 
     memset(byte_count, 0, sizeof(long) * SIZE); 

     inFile = fopen(argv[j], "rb"); // opens the file given on command line 

     if(inFile == NULL)    // error-checking to see if file exists 
     { 
      printf("Files does not exist. `%s`\n", argv[j]); 
      continue; 
     } 

     /* Read the whole file in parts of 1024 */ 
     while((n = fread(buffer, 1, 1024, inFile)) != 0) 
     { 
      /* Add the buffer to the byte_count */ 
      for (i = 0; i < n; i++) 
      { 
       byte_count[(int) buffer[i]]++; 
       length++; 
      } 
     } 
     fclose(inFile); 

     float entropy = entropy_calc(byte_count, length); 
     printf("%02.5f \t%s\n", entropy, argv[j]); 
    } 
    return 0; 
} 

Answer 1

函數entropy_calc()的返回類型應該是float而不是int。