Hi, could someone explain why I am getting two different values in the code below please?

Code:
#import <stdio.h>
#import <string.h>

int main (int argc, const char *argv[])
{
	int inputLength;

	char userInput[10]; 
	
	printf("Enter a number to be reversed: ");
	scanf("%s", &userInput);
	
	inputLength = strlen(userInput);

	printf("inputLength = %i\n\n", inputLength);

	char computerOutput[inputLength];

	printf("\n\ncomputerOutput length = %i", strlen(computerOutput));

	printf("\n\nYour entry of %s is %i characters long.\n\n", userInput, inputLength);

	for (int x = inputLength-1, y = 0; x >= 0; --x, ++y)
		computerOutput[y] = userInput[x];

	printf("computerOutput = %s\n\n", computerOutput);
}
So if I enter 23 at the prompt I get the follwoing output:

inputLength = 2 (yep this is what I expected)

computerOutput length = 21 (What? where is 21 coming from? it should be 2)

Your entry of 23 is 2 characters long. (yep this is what I expected)

computerOutput = 32??????hw???c? (this is 15 long not 21)

I am obviously missing the plot here?

Can someone help please?

Thanks