Text to binary

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

int binary(int n)
{
    long long binaryNumber = 0;
    int remainder, i = 1, step = 1;
    while (n!=0)
    {
        remainder = n%2;
        n /= 2;
        binaryNumber += remainder*i;
        i *= 10;
    }
    return binaryNumber;
}

int main() {
    int n = 0;
    char tobin[1000];
    printf("Enter a string to conver to binary: ");
    fgets(tobin, 1000, stdin);
    do {
    if ((tobin[n] > 255) | (tobin[n] < 0)) {
            printf("Error: Invalid character. Skipping...\n");
            n++;
            continue;
        }
        int answer = binary(tobin[n]), pad = (log10(binary(tobin[n])) + 1), i = 8;
        for (i; i > pad; pad++) {printf("0");}
        printf("%d ", answer);
        n++;
        }
    while (tobin[n] != '\0');
    return 0;
}