# Decimal, Hex, octal and binary number inter conversion

Discussion in 'C' started by shabbir, Oct 5, 2006.

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The article discusses about all the number formats viz Binary, Decimal, Octal, Hex and BCD (Binary coded decimal) and conversion from Decimal to Binary, Octal and Hex and also the reverse conversion.

### Binary

A numbering system based on 2 in which 0 and 1 are the only available digits.

### Decimal

decimal fraction: a proper fraction whose denominator is a power of 10

### Octal

A numbering system that uses eight digits, 0 through 7. It is used as a shorthand system for representing binary characters that use six bits.

### Hexa Decimal

A numbering system which uses a base of 16. The first ten digits are 0-9 and the next six are A-F.

### Binary to Decimal

Code:
```void Bin2Dec()
{
int bin,n,r,s=0,i;
printf("Enter a binary number\n");
scanf("%d",&bin);
n=bin;
for(i=0;n!=0;i++)
{
r=n%10;
s=s+r*(int)pow(2,i);
n=n/10;
}
printf("The equivalent number of %d is %d\n",bin,s);
}
```

### Octal to Decimal

Code:
```void Oct2Dec()
{
int oct,n,r,s=0,i;
printf("Enter an octal number\n");
scanf("%d",&oct);
n=oct;
for(i=0;n!=0;i++)
{
r=n%10;
s=s+r*(int)pow(8,i);
n=n/10;
}
printf("The equivalent number of %d is %d\n",oct,s);
}
```

### Hex to Decimal

Code:
```void Hex2Dec()
{
char hex[N];
int i,j,n[N],l;
long double dec=0;
printf("Enter the hexa decimal number and find it's decimal equivalent\n");
fflush(stdin);
gets(hex);
l=strlen(hex);
for(i=0;i<l;i++)
{
switch(hex[i])
{
case '0':
n[i]=hex[i]-48;     //Ascii code of 0 is 48  48-48=0//
break;
case '1':
n[i]=hex[i]-48;		//Ascii code of 1 is 49  49-48=1//
break;
case '2':
n[i]=hex[i]-48;		//Ascii code of 2 is 50  50-48=2//
break;
case '3':
n[i]=hex[i]-48;		//Ascii code of 3 is 51  51-48=3//
break;
case '4':
n[i]=hex[i]-48;		//Ascii code of 4 is 52  52-48=4//
break;
case '5':
n[i]=hex[i]-48;		//Ascii code of 5 is 53  53-48=5//
break;
case '6':
n[i]=hex[i]-48;		//Ascii code of 6 is 54  54-48=6//
break;
case '7':
n[i]=hex[i]-48;		//Ascii code of 7 is 55  55-48=7//
break;
case '8':
n[i]=hex[i]-48;		//Ascii code of 8 is 56  56-48=8//
break;
case '9':
n[i]=hex[i]-48;		//Ascii code of 9 is 57  57-48=9//
break;
case 'A':
n[i]=hex[i]-55;     //Ascii code of A is 65 65-55=10//
break;
case 'B':
n[i]=hex[i]-55;		//Ascii code of B is 65 66-55=11//
break;
case 'C':
n[i]=hex[i]-55;		//Ascii code of C is 65 67-55=12//
break;
case 'D':
n[i]=hex[i]-55;		//Ascii code of D is 65 68-55=13//
break;
case 'E':
n[i]=hex[i]-55;		//Ascii code of E is 65 68-55=14//
break;
case 'F':
n[i]=hex[i]-55;		//Ascii code of F is 65 69-55=15//
break;
}
}
for(i=0,j=l;i<l;i++,j--)
dec=dec+(n[j-1]*pow(16,i));
printf("The decimal equivalent is %lg \n",dec);
}
```

### Decimal to Binary

Code:
```void Dec2Bin()
{
int n,bin[100],i,j;
printf("Enter A Number To Find It's Binary Equivalence\n");
scanf("%d",&n);
printf("The Binary Equivalent of %d is \t",n);
for(i=0;n!=0;i++)
{
bin[i]=n%2;
n=n/2;
}
for(j=i-1;j>=0;j--)
{
printf("%d",bin[j]);
}
printf("\n");
}
```

### Decimal to Octal

Code:
```void Dec2Oct()
{
int n,r[10],i;
printf("Enter a number to find it's octal equivalent\n");
scanf("%d",&n);
printf("The octal equivalent of %d is ",n);
for(i=0;n!=0;i++)
{
r[i]=n%8;
n=n/8;
}
i--;
for(;i>=0;i--)
printf("%d",r[i]);
printf("\n");
}
```

### Decimal to Hex

Code:
```void Dec2Hex()
{
int n,r[10],i;
printf("Enter a number to get its hexadecimal equivalent\n");
scanf("%d",&n);
for(i=0;n!=0;i++)
{
r[i]=n%16;
n=n/16;
}
i--;
for(;i>=0;i--)
{
if(r[i]==10)
printf("A");
else if(r[i]==11)
printf("B");
else if(r[i]==12)
printf("C");
else if(r[i]==13)
printf("D");
else if(r[i]==14)
printf("E");
else if(r[i]==15)
printf("F");
else
printf("%d",r[i]);
}
printf("\n");
}
```

### Binary Coded Decimal (BCD)

A coding system in which each decimal digit from 0 to 9 is represented by a 4-digit binary number.

#### Attached Files:

• ###### NumberConv.zip
File size:
1.2 KB
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ehsano likes this.
2. ### christinaNew Member

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hi mr. shabbir. i saw your program conversion of decimal nos to binary which is our assignment, here in go4experts.com

uhm...if you dont mind...will please put comments so i will be able to fully understand the program.thanks!
Code:
```void Dec2Bin()
{
int n,bin[100],i,j;
printf("Enter A Number To Find It's Binary Equivalence\n");
scanf("%d",&n);
printf("The Binary Equivalent of %d is \t",n);
for(i=0;n!=0;i++)
{
bin[i]=n%2;
n=n/2;
}
for(j=i-1;j>=0;j--)
{
printf("%d",bin[j]);
}
printf("\n");
}```

Last edited by a moderator: Nov 16, 2006
3. ### christinaNew Member

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if anyone can help me.pls someone put comments in mr. shabbir's program.thank you....

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Where you want me to place the comment I dont understand

5. ### ayat_AceNew Member

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how can i write these programs with assemly languge 8088
thank you

6. ### ayat_AceNew Member

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who can help me

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Its just you who can help yourself. Apart from that if you are stuck somewhere we can.

8. ### ayat_AceNew Member

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thank you mr shabir any way but can help me where i can find the answer so that i can quickl reach it !

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10. ### ayat_AceNew Member

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hi mr shabbir
the answers i mean that you seems to me a very skillful experts so advise me to be good at assemly programming i mean that you know more than me about very powerful websites help me to improve my self in programming

thanks alot
my email : ayat_ace@yahoo.com

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My email add is in the forum. Click on the contact us or also on my profile.

12. ### rai_gandalfNew Member

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Hey Shabbir,
Very useful thread, this one. The thing is one becomes so proficient in programming & concerned with advanced implementation issues, that one often forgets small snippets & nuggets of code such as this. So, Thx a lot for it.

Waise, I developed a Decimal Integer to Binary String or Hexa String Convertor. I have put the source code here ....

Ciao,
Rajiv

Code:
```/* Decimal Integer to Binary String or Hexa String Convertor */

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

#define DEFAULTVAL 0

char* dec_to_binstr(int,int=DEFAULTVAL);
char* dec_to_hexstr(int,int=DEFAULTVAL);

void main()
{
int choice;
unsigned int decqty,numbits;

do{
clrscr();
printf("1. DEC TO BIN\t2. DEC TO HEX\n3. EXIT");
printf("\nEnter choice :  ");
scanf("%d",&choice);

if(choice==1 || choice==2)
{
printf("\n\n\nEnter the Decimal Quantity :  ");
scanf("%d",&decqty);
printf("\nEnter a specific Number of Bits/Hexa-Digits if you want the O/P to contain a specific number of bits");
printf("\n(Enter '0' (or DEFAULTVAL) to leave blank so that program calculates required number of bits) :  ");
scanf("%d",&numbits);
}

switch(choice)
{
default:
case 1:
printf("\n\nBinary Equivalent is :  %s",dec_to_binstr(decqty,numbits));
break;
case 2:
break;
case 3:
break;
}
getch();
}while(choice!=3);
}

/* This Routine Converts a decimal Qty to binary Qty */
char* dec_to_binstr(int decnum,int numbits)
{
int i,j,k;
char *result;
char *temp;

printf("\n\n\nEntered in Routine :  dec_to_binstr()");
printf("\ndecnum = %d\tnumbits = %d",decnum,numbits);

// Calculating Number of bits required
for(i=0;pow(2,i)<abs(decnum);i++);

printf("\nNo. of bits reqd (i) = %d",i);

// Checking Whether 'numbits' provided in Call is adequate
if(numbits!=DEFAULTVAL && numbits<i)
return "ERROR!! Incorrect 'numbits' Specification during Call!!";

// Allocating Memory for 'temp' & 'result'
else if(numbits==DEFAULTVAL)
// No 'numbits' provided in call
{
temp=(char*)malloc((i+1)*sizeof(char));
result=(char*)malloc((i+1)*sizeof(char));
}
else
// Function call has provided the 'numbits'
// Assuming that 'numbits' involves the 1 extra character slot required
// in case of signed integers
{
temp=(char*)malloc((numbits+1)*sizeof(char));
result=(char*)malloc((numbits+1)*sizeof(char));
}

// Performing Intermediate processing on 'temp'
for(j=0;decnum>0;j++)
{
temp[j]=char('0'+decnum%2);
decnum=decnum/2;
}

// Padding Any Bits Remaining if at all with Zeroes
for(;j<numbits;j++)
temp[j]='0';
temp[j]='\0';

// Forming the 'result' string by String Reversal
k=0;

if(numbits==DEFAULTVAL)
j=i-1;
else
j=numbits-1;

for(;j>=0;j--,k++)
result[k]=temp[j];
result[k]='\0';

return result;
}

char* dec_to_hexstr(int decnum,int numbits)
{
int i,j,k;
char *result;
char *temp;
int numtemp;

printf("\n\n\nEntered in Routine :  dec_to_hexstr()!!");
printf("\ndecnum = %d\tnumbits = %d",decnum,numbits);

// Calculating Number of Hexa-digits required
for(i=0;pow(16,i)<abs(decnum);i++);

printf("\nNo. of Hexa-digits reqd (i) = %d",i);

// Checking Whether 'numbits' provided in Call is adequate
if(numbits!=DEFAULTVAL && numbits<i)
return "ERROR!! Incorrect 'numbits' Specification during Call!!";

// Allocating Memory for 'temp' & 'result'
else if(numbits==DEFAULTVAL)
// No 'numbits' provided in call
{
temp=(char*)malloc((i+1)*sizeof(char));
result=(char*)malloc((i+1)*sizeof(char));
}
else
// Function call has provided the 'numbits'
// Assuming that 'numbits' involves the 1 extra character slot required
// in case of signed integers
{
temp=(char*)malloc((numbits+1)*sizeof(char));
result=(char*)malloc((numbits+1)*sizeof(char));
}

// Performing Intermediate processing on 'temp'
for(j=0;decnum>0;j++)
{
numtemp=decnum%16;
if(numtemp>=10)
temp[j]=char('A'+(numtemp-10));
else
temp[j]=char('0'+numtemp);
decnum=decnum/16;
}

// Padding Any Bits Remaining if at all with Zeroes
for(;j<numbits;j++)
temp[j]='0';
temp[j]='\0';

// Forming the 'result' string by String Reversal
k=0;

if(numbits==DEFAULTVAL)
j=i-1;
else
j=numbits-1;

for(;j>=0;j--,k++)
result[k]=temp[j];
result[k]='\0';

return result;
}```

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My pleasure.

Thats a good prog and when I will reach home will try running it.

14. ### christinaNew Member

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hi mr shabbir. i hope you receive my email to you. thank you very much to your program. i ask my other proffessor in school to help me, and he did, at first i dont understand but later on when i spend time (much time n_n' ) on i finally did it. all i can say that somehow, ur a genius sir.hee. coz i dont have the talent you possess. my talent is in drawing, i could be a future flash animator or a web developer.hee.ooopppss!!! why am i saying this.hee.sorry.
But let me give you my WARM-BIG THANKS SIR!!!
my prof gave me a grade of 91 for my effort and hardwork in hios subject.c=
thanks a LOT!!

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christina, the pleasure is all mine but I would suggest one thing. Try to give something to the programming community from where you have got something and that may not necessarily be this forum.

16. ### kunalkunalNew Member

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Need Help!

Hey Shabbir,
Can you help me something?
I am BCA 1st sem. Student; I want a program in C language.

Write a program to transform its input according to a specified transformation scheme. The transformation scheme will consist of two strings: a string of characters and then a string of replacement characters. The idea is that your program replaces every instance of the ith character in the initial string with the (i+3) character (of English alphabets) in the replacement string. When no substitution is defined for a character, the program just passes it through to the output unchanged. The program should inform the user of any errors in the transformation scheme. Your program should display the phrase before and after the substitutions have been made.
Example:
Original String: This is a C program.
String after the transformation: Wklv lv d F Surjudp.

Pls help

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1. Dont jump into others topic / article with your query.
2. Dont ask us to complete your assignments but you can always ask us the best way of doing it.

18. ### kunalkunalNew Member

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you are right but i am new in c programming, then how can i done it ?
so pls give me some tips
thanks

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