Decimal to Binary Program - c

Question

I am working on an assignment for a C Programming course in regards to converting a decimal to binary using a function that takes in an unsigned char as its input and has a void output. The function will print the binary code of the unsigned char. A hint for the assignment is to create an array of exponents starting with 128 and going down to 1.
I started working on the assignment and ran the debugger, but my program is not working and I am getting a run time error message: Run-Time Check Failure #2 - Stack around the variable userInput was corrupted.
I would appreciate some suggestions on how I can fix my code and if there is a much simple way to write it in order to make the code easier to understand.
#include <stdio.h>
#include <stdlib.h>
unsigned char DecimalToBinary(unsigned char decimalInput);
void main() {
unsigned char userInput = ' ';
unsigned char resultOfUserInput = DecimalToBinary(userInput);
printf("Enter a number less than 256: ");
scanf_s("%u", &userInput);
printf("%u in binary: %u", userInput, resultOfUserInput);
system("pause");
}
unsigned char DecimalToBinary(unsigned char decimalNumber) {
int arrayOfExponents[128] = {}, i = 1, j;
while (decimalNumber > 0) {
arrayOfExponents[i] = decimalNumber % 2;
i++;
decimalNumber = decimalNumber / 2;
}
for (j = i - 1; j > 0; j--) {
printf("%i", arrayOfExponents[j]);
}
return 0;
}

Answer 1

%u reads an unsigned int (say 4 bytes) and you are trying to read it into variable userInput (1 byte)

Answer 2

Few things
1) scanf_s("%u", &userInput); please change it to scanf_s("%c", &userInput);
2) You are calling DecimalToBinary before reading user input

Answer 3

#include <stdio.h>
#include <stdlib.h>
unsigned DecimalToBinary(unsigned char decimalInput);
int main(void) {//void is invalid as a return value.
unsigned userInput = 256;
unsigned resultOfUserInput;//DecimalToBinary(userInput);userInput did not input at this point.
printf("Enter a number less than 256: ");
if(1 != scanf_s("%u", &userInput)){
printf("invaid input!\n");
return EXIT_FAILURE;
}
if(userInput >= 256){
printf("More than 256 of the value has been entered.\n");
return EXIT_FAILURE;
}
resultOfUserInput = DecimalToBinary((unsigned char)userInput);
printf("%u in binary: %u\n", userInput, resultOfUserInput);
system("pause");
return 0;
}
unsigned DecimalToBinary(unsigned char decimalNumber) {
unsigned bin = 0, exp = 1;//assert(sizeof(unsigned) >= 4);
while (decimalNumber > 0) {
bin += (decimalNumber & 1) * exp;
decimalNumber >>= 1;
exp *= 10;
}
return bin;
}

Answer 4

This is an easy way to convert numbers from base 10 to any other base using recursion. I have shared one example with you. You can have any other number as your base.
#include <stdio.h>
void baseconvert(int number,int base)
{
if(number > 0)
{
int digit = (number % base);
baseconvert(number / base, base);
printf("%d",digit);
}
else
{
printf("\n");
}
}
int main()
{
baseconvert(1023,2);
return 0;
}