HEXADECIMAL to OCTAL number system conversion in C

 

HEXADECIMAL to OCTAL number system conversion in C

Following program converts a hexadecimal number scanned from user into octal number system and prints the same. The only constraint is this program only converts hexadecimal numbers without any floating points. 

Download C program file to run on your device at the end of this post.
C Program:

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<string.h>
#include<alloc.h>

char* hextobin(char*, int);
char* bintooct(char*,int);
void convert1(char*, char*);
void convert2(char*, char*);
void convert3(char*, char*);
void processing(int,int,char*,char*);
void main()
{
 char hex[100],oct[100],binary[100];
 int n,n2;
 char*ptr;
 char*ptr2;

 clrscr();

 printf("\n Enter HEXADECIMAL NUMBER without any floating point :");
 scanf("%s",hex);
 n= strlen(hex);
 printf("\n length is %d",n);

 ptr=binary;
 ptr=hextobin(hex,n);
 n2= strlen(ptr);

 printf("\n hexadecimal %s is %s in binary.\n",hex,ptr);

 ptr2=oct;
 ptr2= bintooct(ptr,n2);
 printf("\n Binary %s is %s in octal. \n",ptr,ptr2);
 printf( " for more programs visit www.EngineersBurger.com\n -Jay Akbari ");
 getch();

}
//to convert hexadecimal to binary.
char* hextobin(char* hex, int n)
{
 int i,j,k,count=0;
 char* bin;
 char temp[5];
 bin= (char*) malloc(n*4*sizeof(char)+1);

 for(i=0; hex[i]!='\0';i++)
 {
  switch(hex[i])
  {
   case '0': strcpy(temp,"0000");
      break;

   case '1': strcpy(temp,"0001");
     break;

   case '2': strcpy(temp,"0010");
      break;

   case '3': strcpy(temp,"0011");
      break;

   case '4':strcpy(temp,"0100");
     break;

   case '5':strcpy(temp,"0101");
      break;

   case '6':strcpy(temp,"0110");
      break;

   case '7':strcpy(temp,"0111");
      break;

   case '8':strcpy(temp,"1000");
      break;

   case'9' :strcpy(temp,"1001");
      break;

   case'a' :strcpy(temp,"1010");
      break;

   case 'b' : strcpy(temp,"1011");
      break;

   case 'c': strcpy(temp,"1100");
      break;

   case 'd': strcpy(temp,"1101");
      break;

   case 'e': strcpy(temp,"1110");
      break;

   case 'f': strcpy(temp,"1111");
      break;
  }

 k=count;
 for(j=0; temp[j]!='\0';j++)
 {
  *(bin+k)=temp[j];
  k++;
 }

  count=k;

    }

    *(bin+k)='\0';
    return (bin);

}

//to convert binary to octal
char* bintooct(char*ptr,int n)
{   char*temp;

    if( (n%3)==0)
    {
 temp=(char*)malloc( n/3*sizeof(char)+1 );
 convert1(ptr,temp);
 return (temp);
    }

    else if ( (n%3)==1 )
    {
 temp=(char*) malloc(n/3*sizeof(char)+2 );
 convert2(ptr,temp);
 return (temp);
    }

    else //n%3==2
    {
 temp=(char*) malloc(n/3*sizeof(char)+2);
 convert3(ptr,temp);
 return (temp);
    }

}

void convert1(char*ptr,char*temp)
{
    int i,j;

    for(i=0,j=0; *(ptr+i)!='\0';i+=3,j++)
    {
 processing(i,j,ptr,temp);

    }
     *(temp+j)='\0';

}

void convert2(char* ptr,char* temp)
{
   int i,j;

   //checking left most binary is 1 or zero.
 if( *(ptr)=='0')       //eg:0111
  *(temp)='0';
 else
  *(temp)='1';  //eg:1111

   for(i=1,j=1; *(ptr+i)!= '\0';i+=3,j++)
    {

 processing(i,j,ptr,temp);

     }
     *(temp+j)='\0';
}

void convert3(char*ptr, char* temp)
{

   int i,j;

   //checkingthe first two on left most binary is 1 or zero.
 if( *(ptr)=='0'&& *(ptr+1)=='0')       //eg:00 111 111
  *(temp)='0';

 else if (*(ptr)=='0' && *(ptr+1)=='1')
  *(temp)='1';  //eg:01 111 111

 else if( *ptr=='1' && *(ptr+1)=='0' )
  *(temp) ='2';
 else //star of ptr and ptr+1 both are 1
  *(temp)='3';

   for(i=2,j=1; *(ptr+i)!= '\0';i+=3,j++)
    {

  processing(i,j,ptr,temp);

    }
     *(temp+j)='\0';

}
//this function is block of code which is common to above 3 functions.
void processing(int i,int j,char* ptr,char* temp)
{
 if ( *(ptr+i)=='0' && *(ptr+i+1)=='0' && *(ptr+i+2)=='0')
  *(temp+j)='0';

       else if ( *(ptr+i)=='0' && *(ptr+i+1)=='0' && *(ptr+i+2)=='1')
  *(temp+j)='1';

 else if ( *(ptr+i)=='0' && *(ptr+i+1)=='1' && *(ptr+i+2)=='0')
  *(temp+j)='2';

 else if ( *(ptr+i)=='0' && *(ptr+i+1)=='1' && *(ptr+i+2)=='1')
  *(temp+j)='3';

 else if ( *(ptr+i)=='1' && *(ptr+i+1)=='0' && *(ptr+i+2)=='0')
  *(temp+j)='4';

 else if ( *(ptr+i)=='1' && *(ptr+i+1)=='0' && *(ptr+i+2)=='1')
  *(temp+j)='5';

 else if ( *(ptr+i)=='1' && *(ptr+i+1)=='1' && *(ptr+i+2)=='0')
  *(temp+j)='6';

 else // ( *(ptr+i)=='1' && *(ptr+i+1)=='1' && *(ptr+i+2)=='1')
  *(temp+j)='7';
}

Download C program file: CLICK HERE