decimal to hexadecimal

K & R C Programs Exercise 2-3.

Posted on by Sandeepa Nadahalli
K and R C, Solution to Exercise 2-3:
C Function htoi() which converts a string of hexa decimal digits into its equivalent integer value. K and R C Program. Exercises provides the solution to all the exercises in the C Programming Language, second addition, by Brian W.Keringhan and Dennis M.Ritchie(Prentice Hall,1988). You can learn and solve K&R C Programs Exercise. Read more about C Programming Language . 

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#define YES 1
#define NO  0
//HTOI: CONVERT HEXADECIMAL STRING S TO INTEGER
int htoi(char s[])
{
 int hexdigit, i, inhex, n,i=0;
 if(s[i]=='0'){
  ++i;
  if(s[i]=='x' || s[i]=='x')
   ++i;
 }
 n=0;
 inhex=YES;
 for(;inhex==YES;++i){
  if(s[i]>='0' && s[i]<='9')
   hexdigit=s[i]-'0';
  else if(s[i]>='a' && s[i]<='f')
   hexdigit=s[i]-'a'+10;
  else if (s[i]>='A' && s[i]<='F')
   hexdigit=s[i]-'A'+10;
  else
   inhex=NO;
  if(inhex==YES)
   n=16*n+hexdigit;
 }
 return n;
}


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C program to convert a Binary number into its equivalent Decimal, Octal and Hexadecimal numbers.

Posted on by Sandeepa Nadahalli

C Program to convert binary number into its equivalent Decimal, Octal, and Hexadecimal representations. In this program we convert a binary number to decimal. Then convert that decimal number to octal and Hexadecimal equivalent.

The program implements various functions to do the job.

  • binary_to_decimal : Convert given binary number to it’s decimal equivalent
  • decimal_to_octal : Convert from decimal to octal
  • decimal_to_hex : Convert from decimal to hexadecimal

The main function takes care of getting input from user, calling the above functions and displaying the results.

Read more here: What are binary, octal, and hexadecimal notation?

The Program

#include <stdio.h>
/*
* Function to convert a given decimal number to its
* hexadecimal equivalent.
*/
int decimal_to_hex(long number, char *hexstr, int pos) {
long i;
int new_position, n;
char hexchar;
new_position = pos;
if(number > 0) {
i = number % 16;
n = number / 16;
new_position = decimal_to_hex(n, hexstr, pos);
if(i >= 10) {
switch(i) {
case 10: hexchar = 'A'; break;
case 11: hexchar = 'B'; break;
case 12: hexchar = 'C'; break;
case 13: hexchar = 'D'; break;
case 14: hexchar = 'E'; break;
case 15: hexchar = 'F'; break;
}
} else {
hexchar = '0' + i;
}
hexstr[new_position++] = hexchar;
hexstr[new_position] = '\0';
}
return new_position;
}
/*
* Function to convert a given binary number to
* its decimal equivalent.
*/
int binary_to_decimal(int num) {
int rem, base = 1, decimal_number = 0;
while( num > 0) {
rem = num % 10;
if((rem == 0) || (rem == 1)) {
decimal_number = decimal_number + rem * base;
num = num / 10 ;
base = base * 2;
} else {
return -1; // Invalid binary number
}
}
return decimal_number;
}
/*
* Function to convert a given decimal number in to
* its octal equivalent.
*/
int decimal_to_octal(int number) {
int octal_number = 0, rem, base = 1;
while(number > 0) {
rem = number % 8;
octal_number = octal_number + rem * base;
base = base * 10;
number = number / 8;
}
return octal_number;
}
void main() {
int binary_numer, decimal_number, octal_number;
char hexstr[25] = "0";
printf("Enter a binary number: ");
scanf("%d", &binary_numer);
printf("Given Binary number is: %d\n", binary_numer);
decimal_number = binary_to_decimal(binary_numer);
if(decimal_number == -1) {
printf("\nInvalid binary number. Try again.");
return;
}
printf("Its Decimal equivalent is: %d", decimal_number);
octal_number = decimal_to_octal(decimal_number);
printf("\nIts octal equivalent is: %d", octal_number);
decimal_to_hex(decimal_number, hexstr, 0);
printf("\nIts Hexa Decimal equivalent is: %s", hexstr);
}
view raw binary_to_octal_decimal_hexadecimal.c hosted with ❤ by GitHub

Sample Output

Binary to decimal, binary to octal, binary to hexadecimal

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Edit1 : 11th August 2017

  • Added screenshot of sample runs
  • Moved the code to it’s own Gist
  • Modified the program to make it more modular

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