C语言十六进制十进制

#include <stdio.h>
#include<string.h>
int main()
{
  int octaltobinary[]={0,1,10,11,100,101,110,111};
  char hexadecimal[10];
   char hex[10];
  long int binary=0;
  int octal;
  int rem=0;
  int position=1;
  int len=0;
   int k=0;
  printf("Enter a octal number");
  scanf("%d",&octal);
// Converting octal number into a binary number.  
while(octal!=0)
  {
      rem=octal%10;
      binary=octaltobinary[rem]*position+binary;
      octal=octal/10;
      position=position*1000;
  }
  printf("The binary number is : %ld",binary);
  
  // Converting binary number into a hexadecimal number.
  while(binary > 0)
    {
        rem = binary % 10000;
        switch(rem)
        {
            case 0:
                strcat(hexadecimal, "0");
                break;
            case 1:
                strcat(hexadecimal, "1");
                break;
            case 10:
                strcat(hexadecimal, "2");
                break;
            case 11:
                strcat(hexadecimal, "3");
                break;
            case 100:
                strcat(hexadecimal, "4");
                break;
            case 101:
                strcat(hexadecimal, "5");
                break;
            case 110:
                strcat(hexadecimal, "6");
                break;
            case 111:
                strcat(hexadecimal, "7");
                break;
            case 1000:
                strcat(hexadecimal, "8");
                break;
            case 1001:
                strcat(hexadecimal, "9");
                break;
            case 1010:
                strcat(hexadecimal, "A");
                break;
            case 1011:
                strcat(hexadecimal, "B");
                break;
            case 1100:
                strcat(hexadecimal, "C");
                break;
            case 1101:
                strcat(hexadecimal, "D");
                break;
            case 1110:
                strcat(hexadecimal, "E");
                break;
            case 1111:
                strcat(hexadecimal, "F");
            break;
        }
len=len+1;
        binary /= 10000;
    }
  for(int i=len-1;i>=0;i--)
{
    hex[k]=hexadecimal[i];
    k++;
}
hex[len]='\0';
printf("\nThe hexadecimal number is :");
for(int i=0; hex[i]!='\0';i++)
{
    printf("%c",hex[i]);
}
    return 0;
}