C Program To convert a given binary number to equivalent octal, decimal & hexadecimal number

binary_to_octal_decimal_hexadecimal.c

#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);
}