Decimal to Binary conversion using recursion with while loop - c

Question

my binary conversion doesn't work after it recurs a second time, it seems to work only during the first time through. The purpose of the is have a user input a number to convert to Hex, Octal, and brinary from a integer and keep on asking and converting until the user inputs 0. Please help!
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
long toBinary(int);
int main(void) {
int number = 0;
long bnum;
int zero = 0;
while(number != zero) {
puts("\nPlease enter a number you would like to convert to");
puts("\nHexadecimal, octal, and binary: ");
scanf("%d", &number);
if(number != zero) {
printf("\nThe Hexadecimal format is: %x", number);
printf("\nThe Octal format is: %o", number);
bnum = toBinary(number);
printf("\nThe binary format is: %ld\n", bnum);
}
else {
puts("\nI'm sorry you have to enter a number greater than 0.\n");
puts("\nOr have enter an invalid entry.");
}
}
return 0;
}
long toBinary(int number) {
static long bnum, remainder, factor = 1;
int long two = 2;
int ten = 10;
if(number != 0) {
remainder = number % two;
bnum = bnum + remainder * factor;
factor = factor * ten;
toBinary(number / 2);
}
return bnum;
}

Answer 1

You just need a function to convert an integer to its binary representation.
Assuming the int is 32 bits then this should work:
#include <stdio.h>
int main()
{
char str[33];
str[32] = 0;
int x = 13, loop;
for (loop = 31; loop >= 0; --loop) {
str[loop] = (x & 1) ? '1' : '0';
x = x >> 1;
}
printf("As %s\n", str);
return 0;
}
You can make this into a function, read x etc...
EDIT
For octal/hex - printf will do this for you
EDIT
Here goes recursively
#include <stdio.h>
void PrintBinary(int n, int x) {
if (n > 0) {
PrintBinary(n - 1, x >> 1);
}
printf("%c",(x & 1) ? '1' : '0');
}
int main()
{
PrintBinary(32,12);
return 0;
}

Answer 2

First of all I am surprised it even works once. Firstly, your while condition is while number does not equal zero. But right off the bat, number equals 0 and zero equals 0. Therefore the while should never run. If you want to keep this condition for the main loop, change it to a do-while loop: do { //code } while (number != zero);. This will run the code at least once, then check if the inputted number doesn't equal zero. That brings me to the next issue; your scanf for number is scanning for a double and placing it in a regular integer memory spot. Quick fix: scanf("%i",&number);. Also I am finding some functions called puts.. I find it best to keep with one printing function, printf. Now, I am finding afew errors in your toBinary function, but if it works than I guess it works. These are all the errors i could find, I hope this helped. But for future reference there is no need to declare a variable for a const number like 2 or 10 at this level.

Answer 3

#include <stdint.h>
char* toBinary(int32_t number, int index){
static char bin[32+1] = {0}, *ret;
if(index == 32){
memset(bin, '0', 32);
return toBinary(number, 31);
} else if(number & (1<<index))
bin[31-index] = '1';
if(index)
(void)toBinary(number, index-1);
else
for(ret = bin; *ret == '0';++ret);
return ret;
}
...
int number = -1;
...
printf("\nThe binary format is: %s\n", toBinary(number, 32));