c - 如何将二进制数组转换为其 2 的补码？

Question

我在尝试转换为 2 的补码时遇到了问题。我知道问题出在哪里，但我不知道如何解决。问题是内部 for 循环中的两个 if 语句，因为一个将值更改为 0，然后另一个将其更改回 1。我尝试将其更改为 if 和 else if，但随着值的增加，情况变得更糟。

/*
 Signed array[] contains digits of 0 or 1 and at index 0 of the array
 is where it is determined positive or negative. the parameter size is
 the number of digits. Returns the 2's complement of the given array
 with the same number of digits (size of array).
 */

int* signed2Complement2(int signed_binary[], int size){

   int i, j, k;

   int negative = 1;

   int size2 = size;

   int begin_of_array = 0;

   int complement_binary[size];

   if(signed_binary[begin_of_array] == 0){

      negative = 0;

      printf("Is positive %d\n", negative);

   }

   else printf("Is negative %d\n", negative);


   for(i = size-1; i>=0; i--){

       complement_binary[i] = signed_binary[i];

       printf("Binary at %d is: %d\n", i, complement_binary[i]);

   }

   for(j = size2 -1; j>=0; j--){

       if(complement_binary[j] == 1){

          for(k = j; k>=0;k--){

                if(complement_binary[k] == 1){

                complement_binary[k] = 0;

                printf("Binary at %d is: %d\n", k, complement_binary[k]);

             }

             if(complement_binary[k] == 0){

                complement_binary[k] = 1;

                printf("Binary at %d is: %d\n", k, complement_binary[k]);

             }

          }

       }

    }



return complement_binary;

}

Answer 1

我想你是糊涂了我的 friend 。要计算二进制数的补码，有两个步骤:

1.取一个的补码。

2.将一个的补码加1。

所以我的 C 代码是:

int* signed2Complement2(int signed_binary[], int size)
    {
       int i, j, k;
       int negative = 1;
       int size2 = size;
       int begin_of_array = 0;
       int *complement_arr=malloc(size*sizeof(int));
       if(signed_binary[begin_of_array] == 0){
          negative = 0;
          printf("Is positive %d\n", negative);
       }
       else printf("Is negative %d\n", negative);
       for(i=size-1;i>=0;--i)
          if(signed_binary[i]==0)
            complement_arr[i]=1;
          else complement_arr[i]=0;
       i=size-1;
       int carry=1;
       while(i>=0&&carry==1)
       {
           if(complement_arr[i]==0)
           {
              complement_arr[i]=1;carry=0;
           }
           else
           {
               complement_arr[i]=0;carry=1;
           }
           --i;
       }
       return complement_arr;
    }